Method and apparatus for manufacturing minute metallic sphere

ABSTRACT

A manufacturing method of minute metallic spheres of the present invention comprises a heating means for heating and melting a metal to form a metallic sphere, a measurement means for measuring the injected molten metal into a predetermined volume, and a cooling means for cooling the molten metal discharged from the measurement means, to a temperature less than the melting point. The measurement means has a gauger of a predetermined volume in which the molten metal is injected, and is constructed such that the molten metal is cut by rubbing by the predetermined volume by sliding this gauger in contact. The molten metal is injected in the gauger of the predetermined volume to measure, and the measured molten metal is discharged from the gauger to cool to a temperature less than the melting point, and solidified into a sphere in the cooling process.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method and an apparatus formanufacturing minute metallic spheres suitably used for forming a ballbump on an electrode of a semiconductor device, a printed circuit board,or the like.

[0003] 2. Description of the Related Art

[0004] As methods of manufacturing minute metallic spheres withinlow-melting temparature, there are atomization method and a method ofobtaining metallic spheres by dipping a metallic piece made into apredetermined volume in advance, in a heated liquid.

[0005] Besides, in the method described in Japanese Patent ApplicationLaid-open No. 4-74801, a molten metal is extruded from very fineparticles in a liquid heated to a temperature more than the meltingpoint of the metal.

[0006] Although a large quantity of metallic particles can be obtainedfor a short time by the atomization method, it is difficult to make theshapes of the particles uniform in sphere and into an aimed size, andthe yield becomes very bad. By the method of dropping a metallic piecein the heated liquid, it can be made into a substantially completesphere by surface tension. But, for making the sizes of metallic piecesto be dropped, uniform in advance, there are some required processes ofpress-punching a plate made very thin by rolling or the like, or ofmaking into a fine line with a die or the like and accurately cuttingwith a cutter or the like.

[0007] Besides, in that described in the Japanese Patent ApplicationLaid-open No. 4-74801, the interior of a vertical tube is filled with anatural oil or the like, and a zone or a region having a temperaturerange more than the melting point of a metal is provided by a heaterattached to the upper portion of the vertical tube. And, a low-meltingalloy supply tube to which a fine grating is attached in that region, isstood such that the fine grating is at the lower position. A lump of alow-melting alloy is inserted in the low-melting alloy supply tube andmolten, and an inert gas is fed through the upper portion of thelow-melting alloy supply tube. Molten alloy is extruded from the finegrating by the pressure of the gas and made into particles, and theybecome spherical shape by passing through the temperature inclination ofthe vertical tube.

[0008] However, in the method described in this official gazette, therelation between the grating size and the pressurizing force, or thelike, is unknown. In any case, the shape of a particle is made by thesurface tension in a delicate balance relation to such a factor. In thismethod, so-called duplex grain can not be avoided.

SUMMARY OF THE INVENTION

[0009] In consideration of such an actual condition, the presentinvention aims to provide a method and an apparatus for manufacturingminute metallic spheres, capable of accurately and efficientlymanufacturing minute metallic spheres of a predetermined size.

[0010] A manufacturing method of minute metallic spheres of the presentinvention is a manufacturing method of minute metallic spheres formanufacturing minute metallic spheres of a predetermined size, wherein aminute metallic sphere is formed by injecting a molten metal in a gaugerof a predetermined volume to measure, and discharging the measuredmolten metal from the gauger to solidify.

[0011] A manufacturing method of minute metallic spheres of the presentinvention is a manufacturing method of minute metallic spheres formanufacturing minute metallic spheres of a predetermined size, includinga step of heating and melting, a metal to form a metallic sphere, andinjecting the molten metal in a gauger, a step of taking by rubbing themolten metal injected in said gauger by a predetermined volume tomeasure, and a step of discharging the measured molten metal from thegauger, and cooling the molten metal to a temperature less than themelting point to solidify.

[0012] A manufacturing apparatus of minute metallic spheres of thepresent invention is a manufacturing apparatus of minute metallicspheres for manufacturing minute metallic spheres of a predeterminedsize, comprising a heating means for heating and melting a metal to forma metallic sphere, a measurement means for measuring the injected moltenmetal into a predetermined volume, and a cooling means for cooling saidmolten metal discharged from said gauger, to a temperature less than themelting point.

[0013] A manufacturing method of minute metallic spheres of the presentinvention is a manufacturing method of minute metallic spheres formanufacturing minute metallic spheres of a predetermined size, wherein aminute metallic sphere is formed by discharging a molten metal from anopening portion, and dividing said molten metal discharged from saidopening portion into each predetermined volume.

[0014] A manufacturing method of minute metallic spheres of the presentinvention is a manufacturing method of minute metallic spheres formanufacturing minute metallic spheres of a predetermined size, having astep of heating and melting a metal to form a metallic sphere, anddischarging the molten metal from an opening portion, a step of dividingsaid molten metal discharged from said opening portion into eachpredetermined volume, and a step of cooling said molten metal divided toa temperature less than the melting point to solidify.

[0015] A manufacturing apparatus of minute metallic spheres of thepresent invention is a manufacturing apparatus of minute metallicspheres for manufacturing minute metallic spheres of a predeterminedsize, comprising a heating means for heating and melting a metal to forma metallic sphere, a means for discharging the molten metal from apredetermined opening portion, a division means for dividing said moltenmetal having passed through said opening part, and a cooling means forcooling said molten metal divided by said division means, to atemperature less than the melting point.

[0016] A manufacturing method of minute metallic spheres of the presentinvention is a manufacturing method of minute metallic spheres formanufacturing minute metallic spheres of a predetermined size, includinga step of heating and melting a metal to form a metallic sphere, andinjecting the molten metal in a measurement means by pressurizing, astep of cutting by rubbing the molten metal injected in the measurementmeans by a predetermined volume to measure, and a step of dischargingthe measured molten metal from the measurement means by a fluidpressure, and cooling the molten metal to a temperature less than themelting point to solidify.

[0017] A manufacturing apparatus of minute metallic spheres of thepresent invention is a manufacturing apparatus of minute metallicspheres for manufacturing minute metallic spheres of a predeterminedsize, comprising a heating means for heating and melting a metal to forma metallic sphere, a metal supply means for pressurizing and supplyingthe molten metal by the heating means, a measurement means supported soas to be rotatable relatively to said metal supply means, for measuringthe injected molten metal into a predetermined volume by its rotationalaction, and a cooling means for cooling said molten metal dischargedfrom said measurement means, to a temperature less than the meltingpoint.

[0018] A manufacturing apparatus of minute metallic spheres of thepresent invention is a manufacturing apparatus of minute metallicspheres having a measurement unit in an upper portion of an oil vesseldisposed vertically, for forming a minute metallic sphere by solidifyinga molten metal discharged from this measurement unit, in an oil, whereinit has one or a plurality of cooling means in the lower part of saidmeasurement unit, and a lower portion of said oil vessel is cooled.

[0019] A manufacturing method of minute metallic spheres of the presentinvention is a manufacturing method of minute metallic spheres having ameasurement unit in an upper portion of an oil vessel disposedvertically, for forming a minute metallic sphere by solidifying a moltenmetal discharged from this measurement unit, in an oil, wherein one or aplurality of regions in the lower part of said oil vessel is cooled, andthe oil in each region is set and kept at a predetermined temperature.

[0020] A manufacturing apparatus of minute metallic spheres of thepresent invention is a manufacturing apparatus of minute metallicspheres having a measurement unit in an upper portion of an oil vesseldisposed vertically, for forming a minute metallic sphere by solidifyinga molten metal discharged from this measurement unit, in an oil, havingone or a plurality of moving-flow regulation means for physicallyregulating a convection of said oil in the oil vessel in the lower partof said measurement unit.

[0021] A manufacturing method of minute metallic spheres of the presentinvention is a manufacturing method of minute metallic spheres having ameasurement unit in an upper portion of an oil vessel disposedvertically, for forming a minute metallic sphere by solidifying a moltenmetal discharged from this measurement unit, in an oil, wherein aconvection of the oil in the oil vessel is physically regulated in oneor a plurality of portions in the lower part of said measurement unit,and the oil in each region regulated is set and kept at a predeterminedtemperature.

[0022] A manufacturing apparatus of minute metallic spheres of thepresent invention is a manufacturing apparatus of minute metallicspheres having a measurement unit in an upper portion of an oil vesseldisposed vertically, for forming a minute metallic sphere by solidifyinga molten metal discharged from this measurement unit, in an oil, havinga dispersion means for dispersing the molten metal, in the lower part ofsaid measurement unit.

[0023] A manufacturing method of minute metallic spheres of the presentinvention is a manufacturing method of minute metallic spheres having ameasurement unit in an upper portion of an oil vessel disposedvertically, for forming a minute metallic sphere by solidifying a moltenmetal discharged from this measurement unit, in an oil, wherein, in thelower part of said measurement unit, the molten metal discharged fromthe measurement unit, is dispersed.

[0024] A manufacturing apparatus of minute metallic spheres of thepresent invention is a manufacturing apparatus of minute metallicspheres having a measurement unit in an upper portion of an oil vesseldisposed vertically, for forming a minute metallic sphere by solidifyinga molten metal discharged from this measurement unit, in an oil,comprising a molten metal supply apparatus for supplying a molten metalfrom which inclusions have been removed, to the measurement unit.

[0025] A manufacturing apparatus of minute metallic spheres of thepresent invention is a manufacturing apparatus of minute metallicspheres having a measurement unit in an upper portion of a vesseldisposed vertically, for forming a minute metallic sphere by solidifyinga molten metal discharged from this measurement unit, in a coolingmedium put in the vessel, wherein said cooling medium comprises an inerthigh-molecular liquid, an inert high-molecular steam and an inert gas.

[0026] A manufacturing apparatus of minute metallic spheres of thepresent invention is a manufacturing apparatus of minute metallicspheres having a measurement unit in an upper portion of a vesseldisposed vertically, for forming a minute metallic sphere by solidifyinga molten metal discharged from this measurement unit, in a coolingmedium put in the vessel, wherein said cooling medium comprises an oil,and an inert high-molecular liquid put in the lower part of the oil.

[0027] A manufacturing method of minute metallic spheres of the presentinvention is a manufacturing method of minute metallic spheres having ameasurement unit in an upper portion of a vessel disposed vertically inwhich a cooling medium is put, for forming a minute metallic sphere bysolidifying a molten metal discharged from this measurement unit, in thecooling medium put in the vessel, wherein an inert high-molecularliquid, an inert high-molecular steam and an inert gas are used as saidcooling medium, and said molten metal is cooled by said cooling mediumto solidify.

[0028] A manufacturing apparatus of minute metallic spheres of thepresent invention is a manufacturing apparatus of minute metallicspheres having a measurement unit in an upper portion of a vesseldisposed vertically, for forming a minute metallic sphere by solidifyinga molten metal discharged from this measurement unit, in a coolingmedium put in the vessel, wherein the viscosity of said cooling mediumis kept into 2 cSt to 20 cSt at the temperature of 200° C. at which saidmolten metal is melted, and the dropping speed of said molten metal insaid cooling medium is decreased by the viscosity of said coolingmedium.

[0029] A manufacturing method of minute metallic spheres of the presentinvention is a manufacturing method of minute metallic spheres in whicha measured molten metal is discharged in a vessel disposed vertically inwhich a cooling medium is put, and a minute metallic sphere is formed bysolidifying said molten metal in said cooling medium, wherein theviscosity of said cooling medium is kept into 2 cSt to 20 cSt at thetemperature of 200° C. at which said molten metal is melted, and thedropping speed of said molten metal in said cooling medium is decreasedby the viscosity of said cooling medium.

[0030] A semiconductor device according to the present invention is asemiconductor device in which a semiconductor chip and a substrate areelectrically connected by minute metallic spheres of a predeterminedsize, wherein said minute metallic spheres are formed by injecting amolten metal in a gauger of a predetermined volume to measure, anddischarging the measured molten metal from the gauger to solidify.

[0031] A semiconductor device according to the present invention is asemiconductor device in which a semiconductor chip and a substrate areelectrically connected by minute metallic spheres of a predeterminedsize, wherein said minute metallic spheres are manufactured by a methodincluding a step of heating and melting a metal to form a metallicsphere, and injecting the molten metal in a gauger, a step of cutting byrubbing the molten metal injected in said gauger by a predeterminedvolume to measure, and a step of discharging the measured molten metalfrom the gauger, and cooling the molten metal to a temperature less thanthe melting point to solidify.

[0032] According to the present invention, by heating and melting ametal to form a metallic sphere, by a heating means, injecting thismolten metal in a gauger of a predetermined volume, and sliding thisgauger in contact, it can be measured accurately. Further, this measuredmolten metal is discharged from the gauger as it is in the molten state,and cooled by a cooling means to a temperature less than the meltingpoint. The molten metal after measurement solidifies into a sphere bysurface tension in the cooling process, and thereby, a minute metallicsphere of a predetermined size and shape can be obtained with highaccuracy.

[0033] According to the present invention, minute metallic spheres ofthis kind can be manufactured accurately and efficiently. Althoughcontrollability for making the diameters of metallic spheres uniform andmass-productivity in manufacture are not compatible hitherto, massproduction can be made efficiently with high dimensional accuracy, usingthe present invention. Because metallic spheres of an aimed diameter canthus be obtained efficiently, the productivity can be improvedconsiderably.

[0034] According to the present invention, minute metallic spheres of apredetermined size can be manufactured accurately and efficiently.Accordingly, metallic spheres having a desired diameter can be obtainedefficiently, and the productivity can be improved considerably.

[0035] According to the present invention, a metal to form a metallicsphere is heated and melted by a heating means, and this molten metal isinjected in a measurement means of a predetermined volume. In this case,it is pressurized and supplied at a high pressure from one side of themeasurement means, and the other side opposite to it is set to a lowpressure, and, by sliding this measurement means in contact, it can bemeasured accurately. Further, this measured molten metal is dischargedfrom the measurement means as it is in the molten state, and cooled by acooling means to a temperature less than the melting point. The moltenmetal after measurement solidifies into a sphere shape by surfacetension in the cooling process, and thereby, a minute metallic sphere ofa predetermined size and shape can be obtained with high accuracy.

[0036] According to the present invention, by setting/keeping properlythe oil temperature in an oil vessel, and cooling/solidifying a moltenmetal, a minute metallic sphere of good quality can be obtained.Besides, by dispersing the molten metal, the temperature distribution ismade stable, and molten metals are prevented from uniting with eachother, and a minute metallic sphere of good quality can be formedefficiently.

[0037] According to the present invention, by discharging a molten metalin an inert high-molecular liquid as a cooling medium, cleaning aftersolidifying can easily be performed, and it becomes possible to simplifythe cleaning process.

[0038] According to the present invention, it becomes possible to lowerthe dropping speed of a discharged molten metal. Accordingly, it becomespossible to manufacture minute metallic spheres whose sphericity hasbeen improved.

[0039] According to the present invention, by forming minute metallicspheres by the above-described manufacturing methods and apparatus, andusing them for connecting a chip and a substrate in a semiconductordevice, miniaturization of the package of the semiconductor device canbe attained, and the cost can be lowered.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIG. 1 is a sectional view showing an example of a schematicconstruction of a manufacturing apparatus of minute metallic spheresaccording to the first embodiment of the present invention;

[0041]FIG. 2 is a plan view of the manufacturing apparatus of minutemetallic spheres according to the first embodiment of the presentinvention;

[0042]FIG. 3 is a sectional view showing an example of a schematicconstruction of a gauger according to the first embodiment of thepresent invention;

[0043]FIG. 4 is a sectional view showing an example of a schematicconstruction in a modification of the manufacturing apparatus of minutemetallic spheres according to the first embodiment of the presentinvention;

[0044]FIG. 5 is a sectional view of a principal part showing anothermodification of the manufacturing apparatus of minute metallic spheresaccording to the first embodiment of the present invention;

[0045]FIG. 6 is a sectional view showing an example of a schematicconstruction of a manufacturing apparatus of minute metallic spheresaccording to the second embodiment of the present invention;

[0046]FIG. 7 is a plan view showing an upper block of the manufacturingapparatus of minute metallic spheres according to the second embodimentof the present invention;

[0047]FIG. 8 is a plan view showing a stationary plate of themanufacturing apparatus of minute metallic spheres according to thesecond embodiment of the present invention;

[0048]FIG. 9 is a plan view showing a rotational plate of themanufacturing apparatus of minute metallic spheres according to thesecond embodiment of the present invention;

[0049]FIG. 10 is a schematic sectional view showing a principal part ofthe manufacturing apparatus of minute metallic spheres according to thesecond embodiment of the present invention;

[0050]FIGS. 11A to 11C are schematic sectional views showing steps ofmanufacturing minute metallic spheres according to the second embodimentof the present invention, in order of the steps;

[0051]FIG. 12 is a sectional view showing an example of a schematicconstruction of a manufacturing apparatus of minute metallic spheresaccording to a modification of the second embodiment of the presentinvention;

[0052]FIG. 13 is a plan view showing a second rotational plate of themanufacturing apparatus of minute metallic spheres according to themodification of the second embodiment of the present invention;

[0053]FIGS. 14A to 14D are schematic sectional views showing steps ofmanufacturing minute metallic spheres according to modification of thesecond embodiment of the present invention, in order of the steps;

[0054]FIG. 15 is a sectional view showing an example of a schematicconstruction of a manufacturing apparatus of minute metallic spheresaccording to another modification of the second embodiment of thepresent invention;

[0055]FIG. 16 is a sectional view showing a principal part of themanufacturing apparatus of minute metallic spheres according to theother modification of the second embodiment of the present invention;

[0056]FIG. 17 is a sectional view showing an example of a schematicwhole construction of a manufacturing apparatus of minute metallicspheres according to the third embodiment of the present invention;

[0057]FIG. 18 is a perspective view of a principal part of themanufacturing apparatus of minute metallic spheres according to thethird embodiment of the present invention;

[0058]FIG. 19 is a sectional view taken along line III-III′ of FIG. 17,showing an example of the construction of a principal part of themanufacturing apparatus of minute metallic spheres according to thethird embodiment of the present invention;

[0059]FIG. 20 is a partial perspective view showing a rotational drumaccording to the third embodiment of the present invention;

[0060]FIG. 21 is a typical view showing a schematic construction of amanufacturing apparatus of minute metallic spheres according to thefourth embodiment of the present invention;

[0061]FIG. 22 is a typical view showing a schematic construction of amanufacturing apparatus of minute metallic spheres according to amodification of the fourth embodiment of the present invention;

[0062]FIGS. 23A to 23C are typical views showing schematic constructionsof manufacturing apparatus of minute metallic spheres according to othermodifications of the fourth embodiment of the present invention;

[0063]FIG. 24 is a typical view showing a schematic construction of amanufacturing apparatus of minute metallic spheres according to thefifth embodiment of the present invention;

[0064]FIG. 25 is a typical view showing a schematic construction of amanufacturing apparatus of minute metallic spheres according to thesixth embodiment of the present invention;

[0065]FIG. 26 is a typical view showing a schematic construction of themanufacturing apparatus of minute metallic spheres according to thesixth embodiment of the present invention;

[0066]FIG. 27 is a typical view showing a schematic construction of amanufacturing apparatus of minute metallic spheres according to theseventh embodiment of the present invention;

[0067]FIG. 28 is a typical view showing characteristics of oils in theseventh embodiment;

[0068]FIG. 29 is a typical view showing the characteristic of anordinary oil as a comparative example;

[0069]FIGS. 30A and 30B are typical views showing the sphericities ofminute metallic spheres in the seventh embodiment;

[0070]FIG. 31 is a typical view showing the construction of asemiconductor device according to the eighth embodiment; and

[0071]FIG. 32 is a typical view showing a method of arranging minutemetallic spheres in a manufacturing method of the semiconductor deviceaccording to the eighth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0072] First Embodiment

[0073] Hereinafter, a preferred embodiment of method and apparatus formanufacturing minute metallic spheres according to the present inventionwill be described on the basis of drawings.

[0074] Here, first, a minute metallic sphere in this embodiment is anexample made of, e.g., solder in particular. In manufacturing process ofa semiconductor device, in order to connect an electrode portion of asemiconductor element and an external circuit or the like, both arejoined through a bump made of a minute metallic sphere. This minutemetallic sphere suitable for the bump is an object, and, in particular,one having a diameter size of hundreds μm or less is obtained.

[0075]FIG. 1 shows an example of a schematic construction of amanufacturing apparatus of minute metallic spheres used in a method ofthe present invention. In this drawing, 1 and 2 denote upper and lowerblocks for supplying and discharging a molten metal M, 3 denotes a metalthrowing-in portion, 4 denotes an injection passage formed in the upperblock 1, and 5 denotes a discharge port for the molten metal M formed inthe lower block 2.

[0076] In this example, the upper and lower blocks 1 and 2 are, e.g.,circular (see FIG. 2), and fixed to predetermined positions in theapparatus. The upper and lower blocks 1 and 2 are suitably made of amaterial such as a metal, a resin, or a ceramic, that is not wetted withsolder. Or, a coating such as Teflon may be made on the surfaces of onesmade of those materials, and further it is preferable to have a thermalresistance and not to deform with heat.

[0077] As an example of the simplest construction, the injection passage4 and the discharge port 5 may be disposed oppositely in a diameterdirection as shown in FIG. 2.

[0078]6 denotes a gauger set between the upper and lower blocks 1 and 2so as to be rotatable, and 7 denotes a gauging portion provided in thegauger 6. As an example of the simplest construction, it may havegauging portions 7 a and 7 b disposed oppositely in a diameter directionas shown in FIG. 3. The gauging portions 7 a and 7 b are preciselyformed so as to have predetermined volumes. 8 denotes a support shaftfor driving the rotation of the gauger 6.

[0079] In this example, the gauger 6 is suitably made of a material suchas a metal, a resin, or a ceramic, that is not wetted with solder, intoa thin disklike shape. Besides, in the guager 6, a coating such asTeflon may be made on the surfaces of ones made of those materials, andfurther it is preferable to have a thermal resistance and not to deformwith heat. As for the material for making the guager 6, or the like, maybe the same as that for the upper and lower blocks 1 and 2, but it isnot always necessary to made of the same material. When the gauger 6 isset between the upper and lower blocks 1 and 2, it is set closelywithout vertical spaces and to be rotatable. The gauging portions 7 aand 7 b are formed to penetrate the disk of the gauger 6 at positionsthat can correspond to the injection passage 4 and the discharge port 5,respectively.

[0080] Here, other than the case that a pair of gauging portions 7 a and7 b is provided so as to be disposed oppositely as shown in FIG. 3, aplurality of lines or a plurality of pairs can be provided in relationto a circumferential direction (the circumference is divided into fourin the example shown in the drawing) and/or a radial direction (threelines in the example shown in the drawing). In such a case of providinga plurality of gauging portions 7, a plurality of injection portions 4and a plurality of discharge portions 5 are provided in a formcorresponding to the configuration of the gauging portions 7.

[0081] The upper and lower blocks 1 and 2 and parts attendant upon themare accommodated in a vessel (made of glass or the like) 9 in a unitedform, as shown in FIG. 1. Around the vessel 9, a heating coil 10 isdisposed as a heating means for heating and melting a metal to formmetallic spheres. Besides, the interior of the vessel 9 is formed as afluid tank. In this example, an oil 11 is stored as a cooling means forcooling the molten metal M discharged from the gauger 6 to a temperatureless than the melting point.

[0082] The heating coil 10 may be, e.g., a high-frequency coil or thelike, and heats metal thrown in through the metal throwing-in portion 3and keeps it in the state of the molten metal M. The correspondingportion in the vessel 9 to the heating coil 10 is thus set into aheating zone or region. Besides, a portion in the vessel 9 distantdownward from the heating coil 10 is set into a cooling zone or region.By thus providing the heating and cooling zones vertically, atemperature gradient is formed in the vessel 9.

[0083] In the above construction, metal thrown in through the metalthrowing-in portion 3 becomes the state of the molten metal M in theinjection passage 4 by the heating coil 10. The molten metal M isinjected into the gauging portion 7 a positioned just below theinjection passage 4 as shown in FIG. 1. When the gauging portion 7 a isfilled with the molten metal M, then the gauger 6 is driven to rotate bythe support shaft 8. At this time, the upper and lower surfaces of thegauger 6 slide on surfaces of the upper and lower blocks 1 and 2, andconsequently, by cutting the molten metal M into the predeterminedvolume of the gauging portion 7 a by rubbing, it can be measuredaccurately.

[0084] Further, the gauging portion 7 a filled with this measured moltenmetal M moves just above the discharge port 5 positioned on the oppositeside. And, the molten metal M in the gauging portion 7 a is dischargedthrough the discharge port 5 as in the molten state (M1). The dischargedmolten metal M1 descends in the oil 11 of the fluid tank from theheating zone to the cooling zone. In this descent, the molten metal M1is cooled by the oil 11 to a temperature less than the melting point,and, in this cooling process, it solidifies into a spherical shape bysurface tension, and thereby a minute metallic sphere B of apredetermined size and shape is formed with high accuracy.

[0085] By repeating the above operation, the gauging portions 7 a and 7b measure molten metals M alternately, and minute metallic spheres B canbe obtained continually. Accordingly, minute metallic spheres B can bemanufactured with very high accuracy and efficiency.

[0086] Next, the first modification of the method and apparatus formanufacturing minute metallic spheres according to this embodiment willbe described. The same references are used for substantially the samemembers as those of the first embodiment.

[0087]FIG. 4 shows an example of a schematic construction of amanufacturing apparatus of minute metallic spheres according to thefirst modification of this embodiment. In the drawing, 1 and 2 denoteupper and lower blocks for supplying and discharging a molten metal M, 3denotes a metal throwing-in portion, 4 denotes an injection passageformed in the lower block 2, and 5 denotes a discharge port for themolten metal M formed in the lowerblocks 2. In this example, theinjection passage 4 is formed in the lower block 2, and consequently,the molten metal M is supplied from the lower side of a gauger 6.

[0088] The upper block 1 is provided with a degassing port 12 so as tocorrespond to the injection passage 4. This degassing port 12 has arelatively small diameter, and is constricted as shown in the drawing,and made like an orifice. Above the degassing port 12, a storing portion13 for storing a surplus molten metal M is formed continuously. Theupper block 1 is provided also with a gas flow passage 14 so as tocorrespond to the discharge port 5, and nitrogen gas or the like is tobe jetted from this gas flow passage 14 toward the discharge port 5.

[0089] In this embodiment, metal thrown in through the metal throwing-inportion 3 becomes the state of the molten metal M in the injectionpassage 4 by the heating coil 10, like the first embodiment. The moltenmetal M is injected into the gauging portion 7 a positioned just abovethe injection passage 4 as shown in FIG. 4. When the gauging portion 7 ais filled with the molten metal M, then the gauger 6 is driven to rotateby the support shaft 8. At this time, by sliding on surfaces of theupper and lower blocks 1 and 2, the upper and lower surfaces of thegauger 6 can cut the molten metal M into the predetermined volume of thegauging portion 7 a by rubbing, to measure it accurately.

[0090] Further, the gauging portion 7 a filled with this measured moltenmetal M moves just above the discharge port 5 positioned on the oppositeside. And, the molten metal M in the gauging portion 7 a is dischargedthrough the discharge port 5 as in the molten state (M1). In this case,particularly in the first modification, nitrogen gas or the like isjetted from the gas flow passage 14 toward the discharge port 5. Themolten metal M in the gauging portion 7 a is driven in the oil 11 bythis gas pressure, and thereby, the molten metal M is prevented fromremaining in the gauging portion 7 a. Accordingly, an accuratemeasurement can be guaranteed.

[0091] The discharged molten metal M1 descends in the oil 11 of thefluid tank from the heating zone to the cooling zone. In this descent,the molten metal M1 is cooled by the oil 11 to a temperature less thanthe melting point, and, in this cooling process, it solidifies into aspherical shape by surface tension, and thereby a minute metallic sphereB of a predetermined size and shape is formed with high accuracy.

[0092] In case of the above, when the gauging portion 7 a from which themolten metal M has been discharged, is again positioned just above theinjection passage 4, a molten metal M is injected. In this case, theremainder such as a gas in the gauging portion 7 a is completely removedthrough the degassing port 12. Thereby, unevenness of measurements canbe avoided and uniform measurements can be made with high accuracy.Besides, because this degassing port 12 is formed like an orifice, themolten metal M can be injected into the gauging portion 7 a in the formof pressurizing and filling. By thus pressurizing and filling, themolten metal M can evenly be injected into the gauging portion 7 a, and,also in this point, high measurement accuracy can be ensured.

[0093] Here, the second modification of this embodiment will bedescribed.

[0094]FIG. 5 shows the construction of a principal part of this secondmodification. This example has a gauger 17 set between fixed upper andlower blocks 15 and 16 so as to be able to slide (see a both-headedarrow). The gauger 17 is provided with a gauging portion 18. Thisgauging portion 18 is reciprocated between an injection passage 19 ofthe upper block 15 and a discharge port 20 of the lower block 16 atpredetermined timings following the slide of the gauger 17, for example.

[0095] A molten metal M is injected into the gauging portion 18positioned just below the injection passage 19 as shown in FIG. 5. Whenthe gauging portion 18 is filled with the molten metal M, then thegauger 17 is driven to slide as shown in broken lines. At this time, theupper and lower surfaces of the gauger 17 slide on the surfaces of theupper and lower blocks 15 and 16, and consequently, by cutting themolten metal M into the predetermined volume of the gauging portion 18by rubbing, it can be measured accurately.

[0096] The measured molten metal M is discharged through the dischargeport 5 as in the molten state. And, it descends from a heating zone to acooling zone like the above-described embodiment, for example. In thisdescent, it is cooled to a temperature less than the melting point. Inthis cooling process, it solidifies into a spherical shape by surfacetension, and, also in this case, a minute metallic sphere of apredetermined size and shape can thereby be obtained with high accuracy.

[0097] Also in this case, like the first modification shown in FIG. 4,the injection passage 19 can be formed in the lower block 16. In thatcase, a degassing port is provided in the upper block 15, and thereby,the same operation and effect as above can be obtained.

[0098] As the cooling means for the molten metal M, the example of thefluid tank consisting of the oil 11 was described in the aboveembodiment, but, other than this, it can be a fluid tank consisting of,e.g., an inert gas such as argon, nitrogen, or helium. Besides, theapparatus of the present invention is not limited to these fluid tanksbut it can be used in a vacuum atmosphere.

[0099] Next, two examples in which the first embodiment was performedconcretely, will be described.

FIRST EXAMPLE

[0100] First, the first example will be described. This example is anexample of manufacturing metallic spheres having the diameter of 300 μm,and corresponds to the first embodiment or the first modification.

[0101] The upper portion of a vessel 9 of a cylindrical tube filled witha vegetable oil as an oil 11 is heated to 220 to 270° C. by a heatingcoil 10. In this heating zone, a gauger 6 made of a metallic disk havingthe diameter of 150 mm and the thickness of 1 mm is disposed. In theguager 6, gauging portions 7 made of through holes having the diameterof 0.14 mm and formed on the circumference of the diameter of 120 mm atpitch intervals of 10 mm, are provided. The gauger 6 is set betweenupper and lower blocks 1 and 2, and a molten metal M is supplied anddischarged in relation to the gauging portions 7 through an injectionpassage 4 and a discharge port 5. TABLE 1 heating zone yield of metallicspheres of metal composition temperature diameter of 280 to 310 μm NO(%) (° C.) (%) 1 95 Sn-5 Pb 240 75 2 60 Sn-40 Pb 220 68 3 Sn-3.5 Ag-0.7Cu 260 77

[0102] Table 1 shows results of manufacturing metallic spheres in thefirst examples. Clearly from the Table 1, in case of the alloy of anymetal composition, metallic spheres having aimed diameters could bemanufactured at a high yield. As shown in this example, according to thepresent invention, high manufacturing efficiency can be obtained. It maybe said in this connection that the yield of a conventional atomizationmethod is in the degree of 10 to 30% at most.

SECOND EXAMPLE

[0103] The second example is an example of manufacturing metallicspheres having the diameter of 300 μm, and corresponds to the firstembodiment or the first modification.

[0104] A vessel 9 of a cylindrical tube is made into a fluid tank fromthe lower portion of which helium gas is made to flow in, and the upperportion of the vessel 9 is heated to 360 to 450° C. by a heating coil10. In this heating zone, a gauger 6 made of a metallic disk having thediameter of 150 mm and the thickness of 1 mm is disposed. In the guager6, gauging portions 7 made of through holes having the diameter of 0.14mm and formed on the circumference of the diameter of 120 mm at pitchintervals of 10 mm, are provided. The gauger 6 is set between upper andlower blocks 1 and 2, and a molten metal M is supplied and discharged inrelation to the gauging portions 7 through an injection passage 4 and adischarge port 5. TABLE 2 heating zone yield of metallic spheres metalcomposition temperature of diameter of NO (%) (° C.) 280 to 310 μm (%) 11.5 Sn-96.0 Pb-2.5 Ag 350 72 2 1.0 Sn-97.5 Pb-1.5 Ag 380 79 3 83.0Sn-7.0 Pb-10.0 Ag 450 69

[0105] Table 2 shows results of manufacturing metallic spheres in thesecond example. Clearly from the Table 2, in case of the alloy of anymetal composition, metallic spheres having aimed diameters could bemanufactured at a high yield.

[0106] Although the example in which the present invention applied tocases of manufacturing metallic spheres have been described in the aboveembodiments, the present invention is not limited to metallic spheresand can apply to cases of manufacturing minute spheres of glass,plastic, or the like, in the same manner, and, in any case, minutespheres can be manufactured with high accuracy and efficiency.

[0107] Second Embodiment

[0108] Hereinafter, a preferred embodiment of method and apparatus formanufacturing minute metallic spheres according to the second embodimentwill be described on the basis of drawings.

[0109] Here, first, a minute metallic sphere in the embodiment is anexample made of, e.g., solder in particular. In manufacturing process ofa semiconductor device, in order to connect an electrode portion of asemiconductor element and an external circuit or the like, both arejoined through a bump made of a minute metallic sphere. This minutemetallic sphere suitable for the bump is an object, and, in particular,one having a diameter size of hundreds μm or less is obtained.

[0110]FIG. 6 shows an example of a schematic construction of amanufacturing apparatus of minute metallic spheres used in a method ofthe present invention. In FIG. 6, 31 denotes an upper block forsupplying and discharging a molten metal M, 33 denotes a metalthrowing-in portion, and 34 denotes an injection passage formed in theupper block 31. Besides, a through hole 31 a is formed at the center ofthe upper block 1, and a rotational shaft 38 is inserted.

[0111] The injection passage 34 is connected to an injection chamber 32.FIG. 7 shows a plan view of the upperblock 31 from below. Thus, theinjection chamber 32 is formed on the lower surface of the upperblock 31in a recess shape, and around the through hole 31 a in a ring shape. Theupperblock 31 is suitably made of a material such as a metal, a resin,or a ceramic, that is not wetted with solder. Or, a coating such asTeflon may be made on the surfaces of ones made of those materials, andfurther it is preferable to have a thermal resistance and not to deformwith heat.

[0112] To the lower surface of the upper block 31, a stationary plate 36in which holes for discharging a molten metal M are formed is fixed. Arotational plate 7 is disposed in close contact with the stationaryplate 36. The rotational plate 7 is fixed to the rotational shaft 38 andcan rotate together with the rotational shaft 8. The stationary androtational plates 36 and 37 are preferably made of a material having thesame properties as that of the upper block.

[0113] In this example, like the upper block 31, the stationary androtational plates 36 and 37 are, e.g., circular.

[0114] The upperblock 31 and parts attendant upon them are accommodatedin a vessel (made of glass or the like) 39 in a united form, as shown inFIG. 6. Around the vessel 39, a heating coil 40 is provided as a heatingmeans for heating and melting a metal to form a metallic sphere.Besides, the interior of the vessel 39 is formed as a fluid tank. Inthis example, an oil 41 is stored as a cooling means for cooling themolten metal M discharged through the holes 36 a of the stationary plate36, to a temperature less than the melting point.

[0115] The heating coil 40 may be, e.g., an electric heating wire coilor a high-frequency coil or the like, and heats the metal thrown inthrough the metal throwing-in portion 33 and keeps it in the state ofthe molten metal M. The corresponding portion in the vessel 39 to theheating coil 40 is thus set into a heating zone or region. Besides, aportion in the vessel 39 distant downward from the heating coil 40 isset into a cooling zone or region. By thus providing the heating andcooling zones vertically, a temperature inclination is formed in thevessel 39.

[0116] In the above construction, the metal thrown in through the metalthrowing-in portion 33 becomes the state of the molten metal M in theinjection passage 34 by the heating coil 40. The molten metal M isinjected into the injection chamber 32 positioned just below theinjection passage 34 as shown in FIG. 6. When the molten metal M isinjected in the injection chamber 32, then the rotational plate 7 isdriven to rotate by the rotational shaft 38.

[0117]FIG. 8 shows a plan view viewing the stationary plate 36 from thelower part of FIG. 6. In the stationary plate 36, holes 36 a throughwhich a molten metal M is discharged are formed at each predeterminedangle (30 degrees) in two lines concentric around a point O.

[0118]FIG. 9 shows a plan view viewing the rotational plate 37 from thelower part of FIG. 6. In the rotational plate 7, holes 37 a for cuttingthe molten metal M discharged through the holes 36 a of the stationaryplate 36, at each predetermined time, are formed at each predeterminedangle (90 degrees) in two lines concentric around a point O tocorrespond to the radii on which the holes 36 a are formed. The angularpositions at which the holes 36 a and 37 a are formed around the point Oare not limited to the above-described angles. Besides, the holes 36 aand 37 a may not be formed concentrically.

[0119]FIG. 10 shows a section of the stationary and rotational plates 36and 37. Here, FIG. 10 shows a section along an circular arc I-I′ shownin FIG. 8. As shown in this sectional view, a recessed portion 36 b isformed around each hole 36 a in the upper surface of the stationaryplate 36. Besides, each hole 37 a of the rotational plate 37 is soformed as to have a curved surface in section, and an edge 37 b isformed at the upper end. A section of the hole 37 a may be so formed asto have a slanting surface like a taper. Besides, the sectional shape ofthe recessed portion 36 b may also be formed like a taper.

[0120] Because the rotational plate 37 is fixed to the rotational shaft38, the rotational plate 7 is rotated relatively to the stationary plate36 by rotating the rotational shaft 38. Here, when the rotational plate37 is rotated at a constant angular velocity, a hole 37 a of therotational plate 7 and a hole 36 a of the stationary plate 36 areoverlapped at a constant period.

[0121]FIGS. 11A to 11C are sectional views showing, in a time series, astate that the rotational plate 37 is rotated to cut a molten metal M bythe rotational plate 36. Like FIG. 10, FIGS. 11A to 11C also show thesection along the circular arc I-I′ shown in FIG. 8.

[0122] In FIGS. 11A to 11C, the rotational plate 37 moves to the rightside relatively to the stationary plate 36. First, as shown in FIG. 11A,when a hole 37 a of the rotational plate 7 comes to the position of ahole 36 a of the stationary plate 36, and the positions of both areoverlapped, a molten metal M starts to be discharged through the hole 36a of the stationary plate 36.

[0123] And, as shown in FIG. 11B, while the hole 37 a of the rotationalplate 37 is overlapping the hole 36 a of the stationary plate 36, themolten metal M is discharged to hang down from the hole 36 a.

[0124] Further, when the rotational plate 37 is rotated, the moltenmetal M hanging down from the hole 36 a is cut with the edge 37 b of therotational plate 37. And, the cut molten metal M falls in the oil 41.

[0125] As shown in FIG. 6, the molten metal M having fallen in the oil41, descends from the heating zone to the cooling zone in the oil 41 ofthe liquid tank. In this descent, the molten metal M is cooled by theoil 41 to a temperature less than the melting point, and, in thiscooling process, it solidifies into a spherical shape by surfacetension, and thereby, a minute metallic sphere B of a predetermined sizeand shape is formed with high accuracy.

[0126] Because both the holes 37 a of the rotational plate 37 and theholes 36 a of the stationary plate 36 are formed at each constant anglearound the point O, if the rotational plate 37 is rotated at a constantspeed, the period at which a hole 37 a overlaps an arbitrary hole 36 abecomes always constant. Consequently, by making the pressure applied tothe molten metal M on the stationary plate 36 always constant, the sizesof the formed minute metallic spheres B can be uniform. Accordingly, theminute metallic spheres B can be manufactured with very high accuracyand efficiency.

[0127] Next, the first modification of the manufacturing method ofminute metallic spheres according to the second embodiment will bedescribed. FIG. 12 shows an example of a schematic construction of amanufacturing apparatus of minute metallic spheres used in the firstmodification of this embodiment. The manufacturing apparatus of minutemetallic spheres according to the first modification differs from thesecond embodiment in the point that a second rotational plate 42 isprovided on the stationary plate 36. In FIG. 12, the same components asthose of the second embodiment are denoted by the same references.

[0128] In the manufacturing apparatus according to the firstmodification, the injection chamber 32 of the upper block 1 is formedover the second rotational plate 42. And, the molten metal M istemporarily isolated from the stationary plate by the second rotationalplate 42. The second rotational plate 42 is also fixed to the rotationalshaft 38, and, by rotating the rotational shaft 38, the rotational plate37 and the second rotational plate 42 are rotated as one body. Theconstructions other than this, that is, the shape of the stationaryplate 36, the shape of the rotational plate 37, etc., are the same asthose of the first embodiment.

[0129]FIG. 13 shows a plan view of the second rotational plate 42 fromthe lower part of FIG. 12. Thus, a plurality of holes 42 a is formed ateach predetermined angle around the point O in the second rotationalplate 42. And, the radial positions of holes 42 a are formed in twolines so as to correspond to the radial positions of the holes 36 a. Ahole 42 b is a hole for inserting/fixing the rotational shaft 8.

[0130]FIGS. 14A to 14D are sectional views showing, in a time series, astate that the rotational plate 37 and the second rotational plate 42are rotated to cut a molten metal M by rubbing on the stationary plate36 and measure it by the second rotational plate 42, and cut it by therotational plate 36. FIGS. 14A to 14D shows the section along a circulararc II-II′ shown in FIG. 8, in which showing the neighboring hole 36 ain the drawings is omitted.

[0131] In FIGS. 14A to 14D, the rotational plate 37 and the secondrotational plate 42 move to the right side relatively to the stationaryplate 36. First, as shown in FIG. 14A, when a hole 42 a of the secondrotational plate 42 comes to the position of a hole 36 a of thestationary plate 36, and the positions of both are overlapped, a moltenmetal M is poured in the hole 36 a of the stationary plate 36. Asdescribed above, because the position of any hole 37 a of the rotationalplate 37 does not overlap the position of the hole 42 a of the secondrotational plate 42, the molten metal M is not discharged downwardbeyond the hole 36 a in this state.

[0132] And, when the rotational plate 37 and the second rotational plate42 are rotated relatively to the stationary plate 36 as shown in FIG.14B, because the position of the hole 42 a of the second rotationalplate 42 is first shifted in relation to the hole 36 a, the molten metalM stored in the recessed portion 36 b is cut by rubbing so that apredetermined quantity of molten metal M remains in the recessed portion36 b. Thereby, the molten metal M to make a minute metallic sphere ismeasured. Here, the volume of the recessed portion 36 b is so designedas to make the measured molten metal M possible to fall by its ownweight.

[0133] And, as shown in FIG. 14C, the hole 37 a of the rotational plate37 overlaps the hole 36 a of the stationary plate 36. In this, themolten metal M stored in the recessed portion 37 b is discharged to hangdown from the hole 36 a.

[0134] Further, when the rotational plate 37 is rotated, the moltenmetal M hanging down from the hole 36 a is cut with the edge 37 b of therotational plate 37, as shown in FIG. 14D. And, the cut molten metal Mfalls in the oil 41.

[0135] After this, a minute metallic sphere B is formed like the secondembodiment.

[0136] According to the first embodiment described above, because apredetermined quantity of molten metal M can be measured by the secondrotational plate 42, a minute metallic sphere B of a predetermined sizeand shape can be formed with high accuracy.

[0137] Next, the second modification of the second embodiment will bedescribed. In the second embodiment and the first modification, themethod of forming minute metallic spheres by cutting a molten metal Mdischarged by its own weight, at each predetermined time, has beendescribed. The second modification differs from the second embodiment orthe first modification in the point that a predetermined pressure isapplied to the molten metal, and the molten metal M discharged by thispressure is cut at each predetermined time.

[0138]FIG. 15 shows an example of a schematic construction of amanufacturing apparatus of minute metallic spheres according to thesecond modification. In FIG. 15, a metal discharge pipe 43 and arotational blade 44 are disposed in a vessel 39. Like the firstembodiment, around the vessel 39, a heating coil 40 is disposed as aheating means for heating and melting a metal to form metallic spheres.Besides, the interior of the vessel 39 is formed as a fluid tank. Inthis example, an oil 41 is stored as a cooling means for cooling themolten metal M discharged from a hole 36 a of a rotational plate 36 to atemperature less than the melting point.

[0139] The heating coil 40 may be, e.g., an electric heating wire coilor a high-frequency coil or the like, and heats metal thrown in througha metal throwing-in portion 33 and keeps it in the state of the moltenmetal M. The corresponding portion in the vessel 39 to the heating coil40 is thus set into a heating zone or region. Besides, a portion in thevessel 39 distant downward from the heating coil 40 is set into acooling zone or region. By thus providing the heating and cooling zonesvertically, a temperature inclination is formed in the vessel 39.

[0140] Besides, a heating coil 40′ is wound also around the metaldischarge pipe 43 in the oil 41. Here, the heating coil 40′ effects thefunction of making the molten metal M in the metal discharge pipe 43into a molten state, but it is so constructed as to give the coolingzone no heat. By a method not using the heating coil 40′, the moltenmetal M in the metal discharge pipe 43 may be made into a molten stateso as to give the oil 41 in the cooling zone no heat.

[0141] The metal discharge pipe 43 is connected to a pressurizer 45outside the vessel 39. The pressurizer 45 performs its duties ofapplying a predetermined pressure to the molten metal M in the metaldischarge pipe 43, and discharging the molten metal M at a constant ratethrough a metal discharge port 43 a at the front end of the metaldischarge pipe 43.

[0142] The rotational blade 44 can be rotated around a shaft 44 c in thedirection of an arrow B at a constant speed. Four blades 44 a areprovided on the outer circumference of the rotational blade 44.

[0143]FIG. 16 is a perspective view showing the shape of each blade 44a. The front end of the blade 44 a is bent at 90 degrees, and providedwith a cutter 44 b having a U-shaped recessed shape. The recessed shapeof the cutter 44 b corresponds to the position of the metal dischargeport 43 a.

[0144] Next, a method of manufacturing minute metallic spheres using themanufacturing apparatus of minute metallic spheres according to thesecond modification.

[0145] First, a predetermined pressure is applied to the molten metal Min the metal discharge pipe 43 by the pressurizer 45. Thereby, themolten metal M is discharged through the metal discharge port 43 a at aconstant rate. But, here, the molten metal M merely protrudes beyond themetal discharge port 43 a by a predetermined quantity, and does notseparate from the metal discharge port 43 a.

[0146] And, the rotational blade 44 is rotated at a constant speed.Thereby, the cutter 44 b having the U-shaped recessed shape, of a blade44 a cuts the molten metal M protruding beyond the metal discharge port43 a, and the cut molten metal M falls in the oil 41.

[0147] After this, a minute metallic sphere B is formed like the firstembodiment.

[0148] According to the modification 2 of the second embodimentdescribed above, by applying a predetermined pressure to the moltenmetal M, the discharge direction of the molten metal M can be adirection other than the downward direction. Accordingly, for example,it may be constructed to discharge laterally in the vessel 39 and cut.

[0149] Besides, by changing the pressure applied from the pressurizer 45to the molten metal M, the discharge quantity of the molten metal M canbe changed, and, by making the number of rotations of the rotationalblade 44 correspond to this, it is possible to control freely the spherediameter and the manufactured number per unit time.

[0150] Third Embodiment

[0151] Hereinafter, a preferred embodiment of method and apparatus formanufacturing minute metallic spheres according to the third embodimentof the present invention will be described on the basis of drawings.

[0152] Here, first, a minute metallic sphere in this embodiment is anexample made of, e.g., solder in particular. In manufacturing process ofa semiconductor device, in order to connect an electrode portion of asemiconductor element and an external circuit or the like, both arejoined through a bump made of a minute metallic sphere. This minutemetallic sphere suitable for the bump is an object, and, in particular,one having a diameter size of hundreds μm or less is obtained.

[0153]FIG. 17 shows an example of a schematic construction of amanufacturing apparatus of minute metallic spheres used in a method ofthe present invention. In the drawing, 61 and 62 denote outer and innerblocks for supplying and discharging a molten metal M, and 63 denotes arotational drum as a measurement means set between the outer and innerblocks 61 and 62 constituting a metal supply means, so as to be able toslide and rotate.

[0154] The outer and inner blocks 61 and 62 and parts attendant uponthem are accommodated in a vessel (made of glass or the like) 64 in aunited form, as shown in FIG. 17. Around the vessel 64, a heating coil65 is provided as a heating means for heating and melting a metal toform a metallic sphere. Besides, the interior of the vessel 64 is formedas a fluid tank. In this example, an oil 66 is stored as a cooling meansfor cooling the molten metal M discharged from the rotational drum 63,to a temperature less than the melting point.

[0155] Here, the outer and inner blocks 61 and 62 are generallycylindrical or columnar (see FIG. 18), and fixed to predeterminedpositions of the apparatus. These blocks 61 and 62 are suitably made ofa material such as a metal, a resin, or a ceramic, that is not wettedwith solder. Or, a coating such as Teflon may be made on the surfaces ofones made of those materials, and further it is preferable to have athermal resistance and not to deform with heat.

[0156] Besides, the rotational drum 63 is suitably made of a materialsuch as a metal, a resin, or a ceramic, that is not wetted with solder,into a cylindrical shape. Further, in the rotational drum 63, a coatingsuch as Teflon may be made on the surfaces of ones made of thosematerials, and further it is preferable to have a thermal resistance andnot to deform with heat. As for the material for making the rotationaldrum 63, or the like, may be the same as that for the outer and innerblocks 61 and 62, but it is not always necessary to made of the samematerial. When the rotational drum 63 is set between the outer and innerblocks 61 and 62, it is set closely without inside and outside spacesand to be rotatable.

[0157] The rotational drum 63 is driven and rotated by a drive mechanism67, as shown in FIG. 18, for example. The drive mechanism 67 may includea gear sequence such as gears 67 a and 67 b or the like as the exampleshown in the drawing, and it is constructed to drive from the outside.This drive mechanism 67 can control and regulate the rotationaldirection, rotational speed, timing, or the like, of the rotational drum63.

[0158] Next, FIG. 19 shows an example of the construction of a principalpart of an apparatus of the present invention. In the drawing, 68denotes a metal throwing-in portion provided in the outer block 61, and69 denotes an injection passage formed in the outer block 61. The innercircumferential surface of the outer block 61 is formed into acylindrical shape on which the rotational drum 63 slides, and, in partof it, an injection port 69 a (see FIG. 18) as an open end of theinjection passage 69 is opened. Besides, the inner block 62 is providedwith a storage portion 70 disposed oppositely to the injection passage69.

[0159] A molten metal M is pressurized and supplied to the metalthrowing-in portion 68 from a not-shown supply source, and a surplusmolten metal M is stored in the storage portion 70. In this case, thepressure P1 of the molten metal M pressurized and supplied to theinjection passage 69 and the pressure P2 in the storage portion 70 areset such that P1>P2.

[0160] In the lower portion of the outer block 61, a discharge port 71through which a molten metal M1 after measurement is discharged into theoil 66 as described later, is opened. Besides, in the inner block 62, agas chamber 72 for discharging the molten metal M from the rotationaldrum 63, is so disposed as to correspond to the discharge port 71 tosandwich the rotational drum 63. As shown in FIG. 18, a gas supply pipe73 is connected to the gas chamber 72, and an inert gas such as heliumgas is pressurized and supplied.

[0161] The rotational drum 63 as a measurement means has gaugingportions 63 a in which the molten metal M is injected, as shown in FIG.20, for example. The gauging portions 63 a are made of a plurality ofthrough holes of the same size, and each through hole is preciselyformed so as to have the same predetermined volume by the wall thicknessof the rotational drum 63 and its hole diameter. As the example of FIG.20, a plurality of lines of through holes along a longitudinal directionof the rotational drum 63 can be provided. Although the rotational drum63 is driven and rotated by the drive mechanism 67 around the rotationalshaft 74 as described above, it is disposed to correspond to theinjection port 69 a of the injection passage 69 at a predeterminedtiming.

[0162] In case of the above, the heating coil 65 may be, e.g., ahigh-frequency coil or the like, and heats metal thrown in through themetal throwing-in portion 68 and keeps it in the state of the moltenmetal M. The corresponding portion in the vessel 64 to the heating coil65 is thus set into a heating zone or region. Besides, a portion in thevessel 64 distant downward from the heating coil 65 is set into acooling zone or region. By thus providing the heating and cooling zonesvertically, a temperature inclination is formed in the vessel 64.

[0163] In the above construction, metal thrown in through the metalthrowing-in portion 68 becomes the state of the molten metal M in theinjection passage 69 by the heating coil 65. When a gauging portion 63 aof the rotational drum 63 is positioned at the injection port 69 a ofthe injection passage 69 as shown in FIG. 19, the molten metal M flowsin the storage portion 70 of the pressure P2 from the injection passage69 of the pressure P1 through the gauging portion 63 a. By providing apressure difference between the inside and outside of the rotationaldrum 63, the molten metal M can properly be pressurized and filled intothe gauging portion 63 a. Thereby, the molten metal M can evenly beinjected into the gauging portion 63 a, and high measurement accuracycan be ensured efficiently.

[0164] The gauging portion 63 a is thus filled with the molten metal Mwith high accuracy, and then the rotational drum 63 is driven androtated. At this time, the outer and inner circumferential surfaces ofthe rotational drum 63 slide on the outer and inner circumferentialsurfaces of the respective outer and inner blocks 61 and 62, andconsequently, by cutting the molten metal M into the predeterminedvolume of the gauging portion 63 a by rubbing, it can be measuredaccurately.

[0165] Further, the gauging portion 63 a filled with this measuredmolten metal M moves just above the discharge port 71 by the rotation ofthe rotational drum 63. And, the molten metal M in the gauging portion63 a is discharged into the oil 66 as in the molten state (M1) throughthe discharge port 71 by the gas pressure of the gas chamber 72. Thedischarged molten metal M1 descends in the oil 66 of the fluid tank fromthe heating zone to the cooling zone. In this descent, the molten metalM1 is cooled by the oil 66 to a temperature less than the melting point,and, in this cooling process, it solidifies into a sphere by surfacetension, and thereby a minute metallic sphere B of a predetermined sizeand shape is formed with high accuracy.

[0166] By repeating the above operation, a plurality of gauging portionsmeasure molten metals M in order, and minute metallic spheres B can beobtained successively. Accordingly, minute metallic spheres B can bemanufactured with very high accuracy and efficiency. In this manner,according to the present invention, minute metallic spheres B havingaimed diameters can be manufactured at a high yield, and themanufacturing efficiency is considerably improved. It may be said inthis connection that a yield greatly higher than that of a conventionalatomization method can be obtained.

[0167] Here, a modification of the third embodiment will be described.

[0168] As shown in FIG. 19, a plurality of degassing holes 75 can beprovided to be isolated from the discharge port 71 in the outer block61, and suitably to correspond to the respective gauging portions 63 a.These degassing holes 75 are connected to a vacuum source throughnot-shown pipes.

[0169] The degassing holes 75 are not always necessary in case ofproviding the storage portion 70. Consequently, since the molten metal Mis transferred by pressure from the injection passage 69 on the highpressure side through a gauging portion 63 a to the storage portion 70on the low pressure side, it can accurately be measured by thepredetermined volume of the gauging portion 63 a. On the other hand, incase of providing no storage portion 70, if remaining gas or the like ispresent in the gauging portion 63 a, in filling with the molten metal M,it may affect the measurement accuracy. Accordingly, preferably inaccordance with the presence of the storage portion 70, the degassingholes 75 should be provided.

[0170] The gauging portion 63 a from which the molten metal M has beendischarged through the discharge port 71, is disposed to correspond to adegassing hole 75 after it passes through the discharge port 71 by therotation of the rotational drum 63. At this time, the remainder such asa gas in the gauging portion 63 a is completely removed through thedegassing port 75. Thereby, the purity of the gauging portion 63 a afterdischarging the molten metal M is kept, unevenness of measurements canbe avoided, and uniform measurements can always be made with highaccuracy.

[0171] As the cooling means for the molten metal M, the example of thefluid tank consisting of the oil 66 was described in the above thirdembodiment, but, other than this, it can be a fluid tank consisting of,e.g., an inert gas such as argon, nitrogen, or helium. Besides, theapparatus of the present invention is not limited to these fluid tanksbut it can be used in a vacuum atmosphere.

[0172] Next, two examples in which the third embodiment was performedconcretely, will be described.

FIRST EXAMPLE

[0173] First, the first example will be described. This example is anexample of manufacturing metallic spheres having the diameter of 300 μm.

[0174] The upper portion of a vessel 64 of a cylindrical tube filledwith a vegetable oil as an oil 11 is heated to 220 to 270° C. by aheating coil 65. In this heating zone, a rotational drum 63 having thediameter of 120 mm and the thickness of 1 mm is disposed. In therotational drum 63, gauging portions 63 a made of through holes havingthe diameter of 0.14 mm and formed on the circumference at pitchintervals of 10 mm, are provided. The rotational drum 63 is set betweenouter and inner blocks 61 and 62, and a molten metal M is supplied anddischarged in relation to the gauging portions 63 a through an injectionpassage 69 and a discharge port 71. TABLE 3 heating zone yield ofmetallic spheres of metal composition temperature diameter of 280 to 310μm NO (%) (° C.) (%) 1 95 Sn-5 Pb 240 69 2 60 Sn-40 Pb 220 70 3 35 Sn-65Pb 260 71

[0175] Table 3 shows results of manufacturing metallic spheres in thefirst examples. Clearly from the Table 1, in case of the alloy of anymetal composition, metallic spheres having aimed diameters could bemanufactured at a high yield. As shown in this example, according to thepresent invention, high manufacturing efficiency can be obtained. It maybe said in this connection that the yield of a conventional atomizationmethod is in the degree of 10 to 30% at most.

SECOND EXAMPLE

[0176] The second example is an example of manufacturing metallicspheres having the diameter of 300 μm.

[0177] A vessel 64 of a cylindrical tube is made into a fluid tank fromthe lower portion of which helium gas is made to flow in, and the upperportion of the vessel 64 is heated to 360 to 450° C. by a heating coil65. In this heating zone, a rotational drum 63 having the diameter of120 mm and the thickness of 1 mm is disposed. In the rotational drum 63,gauging portions 63 a made of through holes having the diameter of 0.14mm and formed on the circumference at pitch intervals of 10 mm, areprovided. The rotational drum 63 is set between outer and inner blocks61 and 62, and a molten metal M is supplied and discharged in relationto the gauging portions 63 a through an injection passage 69 and adischarge port 71. TABLE 4 heating zone yield of metallic spheres metalcomposition temperature of diameter of NO (%) (° C.) 280 to 310 μm (%) 11.5 Sn-96.0 Pb-2.5 Ag 350 68 2 1.0 Sn-97.5 Pb-1.5 Ag 380 69 3 83.0Sn-7.0 Pb-10.0 Ag 450 65

[0178] Table 4 shows results of manufacturing metallic spheres in thesecond examples. Clearly from the Table 4, in case of the alloy of anymetal composition, metallic spheres having aimed diameters could bemanufactured at a high yield.

[0179] Although examples in which the present invention applied to casesof manufacturing metallic spheres have been described in the above thirdembodiment, the present invention is not limited to metallic spheres andcan apply to cases of manufacturing minute spheres of glass, plastic, orthe like, in the same manner, and, in any case, minute spheres can bemanufactured with high accuracy and efficiency.

[0180] Fourth Embodiment

[0181] Next, the fourth embodiment of the present invention will bedescribed.

[0182] As described in the above-described embodiments, the molten metalM1 discharged from a measurement unit disposed in the vessel 9, becomesa minute metallic sphere B while it descends in the vessel 9. In theprocess of lowering the temperature to the normal temperature in orderto form the minute metallic sphere B, it is very important formanufacturing the minute metallic sphere B of good quality howtemperature history the molten metal M1 is cooled through.

[0183] With the drop of a molten metal M at a high-temperature, when hotoil in the upper portion of the oil vessel is drawn downward, thetemperature of the lower portion of the oil vessel lowers if it is leftas it is. That is, it becomes difficult to cool/solidify the moltenmetal M1 at a proper temperature. This fourth embodiment is mainly toset/keep the oil temperature in the oil vessel proper.

[0184]FIG. 21 shows a schematic construction of the apparatus accordingto this embodiment. In the drawing, an oil 102 is stored in an oilvessel 101, and a measurement unit 100 is disposed in the upper portionin the oil vessel 101. This measurement unit 100 has substantially thesame construction as the apparatus including the guager 6, the upper andlower blocks 3 and 4, etc., described in the above-described embodiment(see FIG. 1). Accordingly, molten metals M1 measured by the measurementunit 100 in the upper portion of the oil vessel 101, are discharged oneafter another.

[0185] A heating coil 103 made of a high-frequency coil or the like,heats metal thrown in the measurement unit 100 and keeps it in a stateof molten metal M1. The region in which this heating coil 103 isdisposed, is set to a heating temperature zone or a heating temperatureregion Z1. One or a plurality of cooling means is provided below themeasurement unit 100. In this example, as the cooling means, it includeswater-cooling tubes and/or cooling jacket 104 and 105 wound around theoil vessel 101 below the measurement unit 100. In the water-cooling tube104 or 105, cooling water is circulated by a pump 106 or 107. Theregions in which the water-cooling tubes 104 and 105 are disposed, areset to cooling temperature zones or cooling temperature regions Z2 andZ3.

[0186] By thus providing the water-cooling tubes and/or cooling jacket104 and 105, the oil 102 is prevented from becoming a high temperatureeven when the molten metal M1 discharged from the measurement unit 100,moves downward, and it is kept at a predetermined low temperature. Atthis low temperature, because the viscosity of the oil 102 becomes largeand its flowability becomes small, a proper temperature distributionalong a vertical direction of the oil vessel 101 can be ensured stably.It is possible to cool the molten metal M1 by temperatures less than themelting point in the cooling temperature zones Z2 and Z3, and tosolidify the molten metal M1 into a sphere in this cooling process.

[0187] Particularly in case of forming a solder minute metallic sphere Bhaving a diameter of 300 to 1000 μm, a large quantity of heat tends tobe transferred downward if the discharge quantity of molten metal M1exceeds 15 g/min. But, even in such a case, the oil temperature in theoil vessel 101 can be set/kept properly by the water-cooling tubes 104and 105.

[0188] In case of the above, though two cooling temperature zones Z2 andZ3 are set as the example shown in the drawing, the number of coolingtemperature zones to be set can be increased or decreased in a relationwith the size of the minute metallic sphere B, the discharge quantity ofmolten metal M1, or the like.

[0189] Next, FIG. 22 shows a modification of the fourth embodiment. Ithas one or a plurality of moving-flow regulation means for physicallyregulating a convection of the oil 102 in the oil vessel 101, below themeasurement unit 100. In this example, as the moving-flow regulationmeans, it includes projecting pieces 108 formed on the inner wall of theoil vessel 101 below the measurement unit 100 to project. In the exampleshown in the drawing, three projecting pieces 108 a, 108 b, and 108 care disposed, and made into pent roof shapes. The projecting pieces 108may be formed continuously or intermittently along the innercircumference of the oil vessel 101.

[0190] By thus providing the projecting pieces 108, with the drop of amolten metal M1 at a high-temperature, the oil 102 at a high temperaturemoving downward or the oil 102 at a low temperature in the lower portionof the oil vessel 101 ascending by the moving flow is suppressed. Eachprojecting piece 108 a, 108 b, or 108 c regulates a convection of theoil 102 in the oil vessel 101, and a cooling temperature zone Z2, Z3, orZ4 can be set at each projecting piece 108, as shown in the drawing. Aproper temperature distribution can be obtained.

[0191] Besides, FIGS. 23A to 23C show other modifications. This examplemainly comprises a dispersion means for the molten metal M1 in the oil102.

[0192] As the dispersion means, a bell-like member 109 of a trigonalpyramid shape is disposed at a position below the measurement unit 100,as shown in FIG. 23A. The bell-like member 109 is typically formed intoa shape widening downward. Besides, the bell-like member 109 is held ata predetermined position of the oil vessel 101 by a support mechanism110, and is to be given a vertical oscillation and a rotational movementby a drive mechanism 111.

[0193] First, by providing the bell-like member 109, with the drop of amolten metal M1 at a high-temperature, the oil 102 at a low temperaturein the lower portion of the oil vessel 101 ascending by a moving flow ofthe oil 102 at a high temperature is suppressed. The bell-like member109 regulates a convection of the oil 102 in the oil vessel 101, and aproper temperature distribution can be obtained.

[0194] Here, when a molten metal M1 at a high-temperature drops, oneline of oil moving-flow arises along the drop path from the upperportion toward the lower portion of the oil vessel 101 if it is left asit is. In the portion of this oil moving-flow, the viscosity of the oil102 becomes small because of the high temperature, and the molten metalM1 concentrates in one portion of this portion to form a passage forheat from the upper portion toward the lower portion of the oil vessel101. Such an oil moving-flow at a high-temperature is undesirablebecause it destroys a proper temperature distribution or balance in theoil vessel 101.

[0195] In such a case, by providing the bell-like member 109, the moltenmetal M1 at a high-temperature discharged from the measurement unit 100can be dispersed so as not to concentrate in one portion, as shown inFIG. 23A. Consequently, by giving the bell-like member 109 a verticaloscillation and a rotational movement by the drive mechanism 111, themolten metal M1 can be dispersed effectively. By dispersing the moltenmetal M1, forming a passage for heat as described above is prevented andthe temperature distribution is made stable, and molten metals M1 areprevented from uniting with each other. At 183° C. or more in case ofSnPb eutectic solder, and at a temperature more than the solidus line incase of solder other than that, the molten metals M1 are prevented fromuniting with each other.

[0196] Besides, in another modification, as shown in FIG. 23B, as thedispersion means, it has propeller stirrers 112 and 113 at a positionbelow the measurement unit 100 or near a middle position of the oilvessel 101. The propeller stirrers 112 and 113 are to be given arotational movement around a vertical axis by a not-shown drivemechanism. In this example, the propeller stirrer 112 is disposed nearthe lower portion of the heating temperature zone Z1, and the propellerstirrer 113 is disposed downward at a predetermined distance from thepropeller stirrer 112.

[0197] First, by providing the propeller stirrers 112 and 113 having astirring function, the oil 102 in the oil vessel 101 can be stirred.Particularly in case of having a step portion 101a near the lowerportion of the heating temperature zone Z1 as this example, by thepropeller stirrer 112 rotating, the movement of the oil 102 betweenzones, that is, a convection of the oil 102 that is to move from thelower part thereof to the heating temperature zone Z1, can besuppressed, and each zone can be set/kept at a proper temperature.

[0198] Besides, by providing the propeller stirrers 112 and 113, bystirring the oil 102 at a temperature more than the solidus line, themolten metal M1 at a high-temperature discharged from the measurementunit 100 can be dispersed in the oil 102. By thus dispersing the moltenmetal M1, it is prevented from concentrating in one portion, and moltenmetals M1 can be prevented from uniting with each other. At 183° C. ormore in case of SnPb eutectic solder, and at a temperature more than thesolidus line in case of solder other than that, the molten metals M1 areprevented from uniting with each other.

[0199] Besides, in another modification, as shown in FIG. 23C, as thedispersion means, it includes supersonic oscillators 114 (114 a and 114b) and 115 (115 a and 115 b) at a position below the measurement unit100 or near a middle position of the oil vessel 101. The supersonicoscillators 114 and 115 are to oscillate supersonic waves by a not-showndrive device. In this example, the supersonic oscillator 114 is disposednear the lower portion of the heating temperature zone Z1, and thesupersonic oscillator 115 is disposed downward at a predetermineddistance from the supersonic oscillator 114. The oscillation directionby these supersonic oscillators 114 and 115 is suitably a horizontaldirection from the inner wall of the oil vessel 101 toward a vicinity ofthe central portion.

[0200] By providing the supersonic oscillators 114 and 115 having anoscillation function, by applying supersonic waves in the oil 102 at atemperature more than the solidus line, the molten metal M1 at ahigh-temperature discharged from the measurement unit 100 can bedispersed in the oil 102. By thus dispersing the molten metal M1, it isprevented from concentrating in one portion, and molten metals M1 can beprevented from uniting with each other. At 183° C. or more in case ofSnPb eutectic solder, and at a temperature more than the solidus line incase of solder other than that, the molten metals M1 are prevented fromuniting with each other.

[0201] Fifth Embodiment

[0202] Next, the fifth embodiment of the present invention will bedescribed.

[0203] A minute metallic sphere B is used for forming a bump on anelectrode of a semiconductor device or the like. It is important thatthe molten metal M used in each of the above embodiments, does notcontain inclusion, oxide, or the like, (hereinafter, simply calledinclusion), and has a high purity, in order to form a minute metallicsphere B of good quality.

[0204] This embodiment is to obtain a molten metal M at a high purity asa material for forming a minute metallic sphere B, from a materialmetal.

[0205]FIG. 24 shows a schematic construction of an apparatus accordingto this embodiment. This apparatus is disposed before a measurement unit100, and supplies a molten metal M to the measurement unit 100. In thedrawing, 116 denotes a pot for storing the molten metal M, and 117denotes a heating coil made of a high-frequency coil or the like toset/keep the interior of the pot 116 at a temperature more than themelting point of a material metal (solder material) M0. The materialmetal M0 is conveyed by a conveyer 118 to the upper portion of the pot116, and thrown in the pot 116.

[0206] Besides, in the drawing, 119 denotes an overflow hole or pipe fordischarging inclusion, provided near the upper portion of the pot 116,120 denotes a supply pipe for a molten metal M, connected to the lowerend of pot 116, 121 denotes an inert gas supply hole or pipe connectedto the middle of the supply pipe 120, and 122 denotes a ceramic filterprovided below the inert gas feed pipe 121. The mesh size of the ceramicfilter 122 is preferably 0.2 μm or less.

[0207] An inert gas (may be argon gas, helium gas, or the like) fed fromthe inert gas feed pipe 121, is blown out through the bottom portion ofthe pot 116, and ascends in the molten metal M. Inclusion in the moltenmetal M is caught by the inert gas ascending in the molten metal M. And,it surfaces on the liquid surface of the molten metal M, and isdischarged through the overflow pipe 119. By inclusion beingcaught/discharged, the molten metal M in the pot 116 is purifiedgradually.

[0208] The molten metal M in the pot 116 then passes through the ceramicfilter 122, and is supplied to the measurement unit 100 by the supplypipe 120. By removing inclusion and further passing through the ceramicfilter 122, the molten metal M having a very high purity can beobtained. For comparing with a wire cut ball formed using a normalsolder material, when a section of a minute metallic sphere Bmanufactured according to the present invention was analyzed, incomparison with the content of inclusion of 100 ppm level contained inthe former, it could be decreased to the degree of 10 ppm levelaccording to the present invention. By using a molten metal of highpurity, a minute metallic sphere B with very good joinablity to anelectrode of a semiconductor device, or the like, can be formed.

[0209] Although the present invention has been described with referenceto the examples of concrete numerical values or the examples shown inthe drawings in the above embodiments, the present invention is notlimited to only those examples shown in the drawings, or the like, butcan be variously modified or the like within the scope of the presentinvention.

[0210] For example, the disposed positions or the quantity of thecooling means, the moving-flow regulation means, or the like, in theabove embodiments, can be properly changed at need. Besides, theconcrete shapes or the like of the bell-like member, the propellerstirrer, or the like, can employ other shapes properly.

[0211] Sixth Embodiment

[0212] Hereinafter, a preferred embodiment of method and apparatus formanufacturing minute metallic spheres according to the sixth example ofthe present invention will be described on the basis of drawings.

[0213] As described in each of the above-described embodiments, afterthe process of lowering the temperature of the molten metal M1 using acooling medium such as an oil for forming a minute metallic sphere B, isperformed, it is necessary to remove the cooling medium from the surfaceof the minute metallic sphere B. This is because the joinability injoining by reflow to a semiconductor chip, substrate, or the like,deteriorates if it is left in the state that the cooling medium such asan oil adheres.

[0214] The sixth embodiment is to make it possible easily to remove thecooling medium from the surface after a minute metallic sphere B isformed.

[0215]FIG. 25 is a typical view showing a manufacturing apparatus ofminute metallic spheres B according to the sixth embodiment. In FIG. 25,a liquid cooling medium (fluorine-type high-molecular liquid 130) is putin a vessel 101. A measurement unit 100 is disposed in the upper portionof the vessel 101. Molten metals M1 are discharged one after anotherfrom this measurement unit 100, like each of the above-describedembodiments. The discharged molten metal M1 is made into a sphere in thecooling medium by surface tension.

[0216] A heating coil 103 made of a high-frequency coil or the like isdisposed around the vessel 101. Also in the manufacturing apparatus ofminute metallic spheres B of this embodiment, a predetermined coolingmeans such as a water-cooling tube and/or cooling jacket is provided soas to form a predetermined temperature inclination from the position atwhich the measurement unit 100 is disposed, toward the lower part, butit is omitted in the drawing here.

[0217] The cooling medium in this embodiment is made of a fluorine-typehigh-molecular liquid (fluorine-type inert liquid) 130, and put in fromthe bottom of the vessel 101 to the upper portion of measurement unit101. The fluorine-type high-molecular liquid 130 is a liquid having achemical formula of, e.g., (C₅F₁₁)_(3n), and has a specific gravity inthe degree of 1.2 or more. In the fluorine-type high-molecular liquid130, the greater the specific gravity is, the more the number ofsubstitutions of fluorine is. As an example of such a fluorine-typehigh-molecular liquid 130, the trade name Frorinate made by Sumitomo 3MLimited can be given.

[0218] The molten metal M1 measured by the measurement unit 100 isdischarged in the fluorine-type high-molecular liquid 130 in the vessel101 as it is in the molten state. The discharged molten metal M1 dropsdownward in the fluorine-type high-molecular liquid 130 as it is madeinto a sphere. Because the boiling point of the fluorine-typehigh-molecular liquid 130 is stable in the degree of 150° C. to 215° C.and it does not react with solder or the like constituting the moltenmetal M1, the molten metal M1 is cooled in accordance with thetemperature inclination of the fluorine-type high-molecular liquid 130as it is dropping downward in the vessel 101. And, about the time whenthe discharged molten metal M1 reaches the bottom of the vessel 101, themolten metal M1 has solidified to form a minute metallic sphere B.

[0219] The molten metal M1 having become a solid is taken out from thefluorine-type high-molecular liquid 130, and cleaned. Because thefluorine-type high-molecular liquid 130 is superior in cleanability, thefluorine-type high-molecular liquid 130 adhering to the surface of theminute metallic sphere B can easily be removed by using alcohol such asethanol, or acetone.

[0220] The high-molecular liquid is not limited to fluorine-type, butvarious inert high-molecular liquids can be used. Besides, it may be onein which several kinds of inert high-molecular liquids are mixed.Besides, for example, it may be one in which several kinds of inerthigh-molecular liquids different in the above-described number ofsubstitutions of fluorine are mixed.

[0221] Besides, although the manner that the molten metal M1 dischargedfrom the measurement unit 100 is cooled by the liquid fluorine-typehigh-molecular liquid 130, it is also possible that the vessel 101 isfilled with gas (steam) of the fluorine-type high-molecular liquid 130and the molten metal M1 discharged in the gas atmosphere is cooled. Inthis case, it is desirable that a liquid cooling medium is further putin below the gas to perform further cooling.

[0222] As described above, according to the sixth embodiment of thepresent invention, by discharging the molten metal M1 in thefluorine-type high-molecular liquid 130 as a cooling medium, cleaningafter solidifying can easily be performed, and it becomes possible tosimplify the cleaning process.

[0223] Next, a preferred embodiment of method and apparatus formanufacturing minute metallic spheres according to an modification ofthe sixth embodiment of the present invention will be described on thebasis of drawings.

[0224] The modification of the sixth embodiment is also to make itpossible easily to remove a cooling medium after a minute metallicsphere B is formed like the sixth embodiment.

[0225]FIG. 26 is a typical view showing a manufacturing apparatus ofminute metallic spheres B according to the modification of the sixthembodiment. In FIG. 26, a cooling medium consisting of two kinds ofliquids is put in a vessel 101. That is, in the vessel 101, such an oil102 as described in the above first to fifth embodiments and such afluorine-type high-molecular liquid 130 as described in the sixthembodiment, are put in. Because the fluorine-type high-molecular liquid130 has a specific gravity of 1.2 or more as described above, and theoil 102 has a specific gravity in the degree of 0.8, both separate at aboundary 131 so that the oil 102 is positioned on the upper portion ofthe fluorine-type high-molecular liquid 130.

[0226] A molten metal M1 discharged from the measurement unit 100 isfirst discharged in the oil 102. The oil 102 is kept at a predeterminedtemperature by the heating coil 103 disposed outside the vessel 101,where the molten metal M1 is made into a sphere by surface tension inthe oil 102.

[0227] After this, the molten metal M1 drops downward in the oil 102,and soon gets beyond the boundary 131 surface to the fluorine-typehigh-molecular liquid 130, and drops in the fluorine-type high-molecularliquid 130. Also in the fluorine-type high-molecular liquid 130, apredetermined temperature inclination is set downward by the heatingcoil 103, a cooling tube, or the like, the molten metal M1 solidifies asit is dropping downward. At the same time, the oil 102 adhering to thesurface of the molten metal M1 comes off in the fluorine-typehigh-molecular liquid 130, and the surface of the molten metal M1 iscovered with the fluorine-type high-molecular liquid 130.

[0228] That is, by transferring the molten metal M1 from the oil 102into the fluorine-type high-molecular liquid 130, the oil 102 adheringto the surface of the molten metal M1 can completely be removed. Themolten metal M1 having solidified into a solid is taken out from thefluorine-type high-molecular liquid 130, and cleaned. Because thefluorine-type high-molecular liquid 130 is superior in cleanability, thefluorine-type high-molecular liquid 130 adhering to the surface of theminute metallic sphere B can easily be removed by using alcohol such asethanol, or acetone. Accordingly, differently from the case of coolingonly with the oil 102, it becomes possible easily to perform cleaningafter the molten metal M1 has solidified to form a minute metallicsphere B.

[0229] As shown in FIG. 26, the oil 102 and the fluorine-typehigh-molecular liquid 130 separate completely at the boundary 131because of the difference in specific gravity. Besides, if thefluorine-type high-molecular liquid 130 is made to contain alcohol suchas methanol or ethanol, soil such as oil adhering to the surface of themolten metal M1, can be decomposed by alcohol, and, in addition, becausealcohol and the fluorine-type high-molecular liquid 130 separate, byremoving components such as soil together with alcohol from thefluorine-type high-molecular liquid 130, it becomes possible toregenerate the fluorine-type high-molecular liquid 130.

[0230] As described above, according to the modification of the sixthembodiment, after discharging a molten metal M1 from the measurementunit 100 into the oil 102, by transferring it into the fluorine-typehigh-molecular liquid 130, the oil 102 adhering to the surface of themolten metal M1 can be removed, and it becomes possible easily toperform cleaning after solidification.

[0231] Seventh Embodiment

[0232] Hereinafter, a preferred embodiment of method and apparatus formanufacturing minute metallic spheres according to the seventhembodiment of the present invention will be described on the basis ofdrawings.

[0233] As described in each of the above embodiments, e.g., in the sixthembodiment, the molten metal M1 discharged from the measurement unit 100drops downward in a cooling medium such as oil, and is cooled withdropping by the temperature inclination of the cooling medium set by theheating coil 103, a cooling tube, or the like, to become a minutemetallic sphere B.

[0234] Here, the dropping speed of the molten metal M1 in the coolingmedium greatly affects on the sphericity when the molten metal M1 hassolidified to become a minute metallic sphere B, and the sphericitydeteriorates due to the resistance of the cooling medium when the speedis large. Accordingly, it is very important for manufacturing a minutemetallic sphere B of good quality to control properly the dropping speedin the cooling medium. The seventh embodiment is to control the droppingspeed in the cooling medium and to improve the sphericity of the minutemetallic sphere B.

[0235] As described before, the manufactured minute metallic sphere B isused as a bump for connecting an electrode portion of a semiconductorelement and an external circuit or the like in a manufacturing processof a semiconductor device. The size of the minute metallic sphere isdetermined in accordance with the sizes of the respective electrodes ofthe semiconductor element and the external circuit, or the like, andvarious sizes of minute metallic spheres are used in accordance withapplication/object.

[0236] Here, because the dropping speed in the cooling medium is inproportion to the square of the radius of the minute metallic sphere B,when minute metallic spheres B having sizes in the degree of 100 μm indiameter, are manufactured, the dropping speeds little affect on thesizes of the minute metallic spheres B.

[0237] But, according to a kind of semiconductor device, minute metallicspheres B having diameters in the degree of 400 μm to 800 μm, are used,and, in case of forming such a relatively large minute metallic sphereB, it is required in particular to control the dropping speed in thecooling medium.

[0238] In this embodiment, when minute metallic spheres B havingdiameters in the degree of 400 μm to 800 μm, are manufactured, an oilwhose viscosity becomes high near the melting point of the minutemetallic spheres B, is used.

[0239]FIG. 27 is a typical view showing the construction of amanufacturing apparatus of minute metallic spheres B according to theseventh embodiment. As shown in FIG. 27, also in the manufacturingapparatus of minute metallic spheres B according to the seventhembodiment, it comprises a vessel 101, a measurement unit 100 disposedin the vessel 101, and an oil 135 put in the vessel 101 and put in tothe upper portion of the measurement unit 100. Besides, a heating coil103 is disposed on the outer circumference of the vessel 101.

[0240] As shown in FIG. 27, the oil 135 put in the oil 135 is heated toa predetermined temperature by the heating coil 103 in a heating zone,and forms a downward temperature inclination by a member such as anot-shown cooling tube in a cooling zone. Here, the dropping speedbecomes a problem mainly in the upper portion of the cooling zone.

[0241] Because, in general, the higher the temperature is, the lower theviscosity of oil is, decrease in dropping speed due to decrease inviscosity becomes remarkable particularly near the cooling zone set to atemperature near the melting point of the molten metal M1.

[0242]FIG. 28 is a typical result showing the characteristic of oils 135in the seventh embodiment. Besides, FIG. 29 shows the characteristic ofan ordinary oil for comparison. Here, FIGS. 28 and 29 show the viscosityat temperatures of 40° C., 100° C., and 200° C.

[0243] As shown in FIG. 28, the oils 135 used in this embodiment arethree kinds shown in {circle over (1)} to {circle over (3)} for example,and the viscosity is set in the range of 8 cSt to 7.6 cSt at 200° C. Onthe other hand, in the ordinary oil {circle over (4)} as shown in FIG.29, the viscosity at 200° C. is in the degree of 1.0 cSt. In theviscosity of 1.0 cSt, a minute metallic sphere B having a diameter of400 μm to 800 μm drops at a very high dropping speed, and change of thesphericity becomes great due to the resistance at this time, but, byusing an oil having a viscosity more than the degree of 6 to 7 cSt at200° C. as this embodiment, it becomes possible to decrease the droppingspeed of the molten metal M1 discharged from the measurement unit 100.The above viscosity may be ensured by mixing several kinds of oilsdifferent in viscosity as the oil 135, and the above viscosity may beensured by mixing a viscosity improver in.

[0244]FIG. 30A shows sphericities in case of using the oil 135 of{circle over (1)} shown in FIG. 28. Besides, FIG. 30B shows sphericitiesin case of using the oil shown in FIG. 29. Thus, by increasing theviscosity at 200° C., the sphericity of a completed minute metallicsphere B can be improved.

[0245] On the other hand, in the lower portion of the cooling zone, thatis, in the lower portion of the vessel 101, because a solidified minutemetallic sphere B must be taken out, there can not be used an oil havinga high viscosity. In this embodiment, as shown in FIG. 28, because anoil having a viscosity in the degree of 100 cSt to 400 cSt at 40° C. isused, it becomes possible to take out the solidified minute metallicsphere B. In general, if the viscosity at a high temperature is great,because the viscosity at a low temperature is also great, it is supposedthat a hindrance arises in taking out. For example, when the viscosityis in the degree of 1000 cSt, the oil becomes syrupy, and it isdifficult to take out a minute metallic sphere B from there. In the oil135 used in this embodiment, in spite of a great viscosity at 200° C.for decreasing the dropping speed, the viscosity at 40° C. is suppressedto the degree of 400 cSt or less. Accordingly, a predetermined viscosityat which the dropping speed can be suppressed to a small value, can beensured in the upper portion of the cooling zone, and it can be a lowviscosity necessary for taking out in the lower portion of the coolingzone.

[0246] As described above, according to the seventh embodiment of thepresent invention, it becomes possible to decrease the dropping speed ofthe molten metal M1 discharged from the measurement unit 100.Accordingly, it becomes possible to manufacture a minute metallic sphereB whose sphericity has been improved.

[0247] Besides, because the viscosity of the oil 135 is set such thatthe viscosity at a low temperature is not greater than a predeterminedvalue even when the viscosity at a high temperature is great, it becomespossible easily to take out a solidified minute metallic sphere B fromthe oil 135.

[0248] Eighth Embodiment

[0249] Next, the eighth embodiment of the present invention will bedescribed. The eighth embodiment is that minute metallic spheres B inthe above embodiments are applied to a semiconductor device. FIG. 31 isa schematic sectional view showing the construction of a semiconductordevice according to this embodiment. The semiconductor device 140according to this embodiment is that a semiconductor chip 141 and asubstrate 142 are connected through minute metallic spheres 143.

[0250] The substrate 142 shown in FIG. 31 is a TAB tape, and consists ofleads 142 a and a film base 142 b. The semiconductor chip 141 is thatcircuits are formed on a semiconductor substrate such as silicon by anordinary process.

[0251] The minute metallic spheres 143 are disposed on the semiconductorchip 141 or the substrate 142, and the semiconductor chip 141 and thesubstrate 142 are connected through the minute metallic spheres 143 by,e.g., reflow. It is packaged with a sealing resin 144 in the state thatthe semiconductor chip 141 and the substrate 142 are connected. In thissemiconductor device 140, because connecting by wire bonding is notperformed, the package of the semiconductor device 140 can be formedwithout excessively enlarging from the outer shape of the semiconductorchip 141.

[0252] Disposition of the minute metallic spheres 143 on thesemiconductor chip 141 can be performed by, e.g., the method shown inFIG. 32. A mold 145 made of a stainless thin plate in which throughholes 145 a having a diameter slightly smaller than the diameter of theminute metallic spheres 143 are opened so as to correspond to thepositions of electrodes on the semiconductor chip 141 or the substrate142, is prepared, and, by sucking the portion of the through holes 145 aof this mold by a vacuum pump, the minute metallic spheres 143 areadsorbed to the positions of through holes 145 a, and, after the minutemetallic spheres 143 disposed on the mold 145 are placed on theelectrodes on the semiconductor chip 141 or the substrate 142, suctionis stopped to dispose the minute metallic spheres 143 on the electrodes.

[0253] As described above, according to the eighth embodiment of thepresent invention, by forming the minute metallic spheres by methods andapparatus of the first to seventh embodiments, and using them forconnecting the semiconductor chip 141 and the substrate 142 of thesemiconductor device 140, miniaturization of the package of thesemiconductor device 140 can be attained, and the manufacturing cost canbe lowered.

What is claimed is:
 1. A manufacturing method of minute metallic spheresfor manufacturing minute metallic spheres of a predetermined size,wherein a minute metallic sphere is formed by injecting a molten metalin a gauger of a predetermined volume to measure, and discharging themeasured molten metal from the gauger to solidify.
 2. A manufacturingmethod of minute metallic spheres described in claim 1, wherein saidmolten metal discharged from said gauger is cooled to a temperature lessthan the melting point, and solidified into a sphere in the coolingprocess.
 3. A manufacturing method of minute metallic spheres formanufacturing minute metallic spheres of a predetermined size, includinga step of heating and melting a metal to form a metallic sphere, andinjecting the molten metal in a gauger, a step of taking by rubbing themolten metal injected in said gauger by a predetermined volume tomeasure, and a step of discharging the measured molten metal from thegauger, and cooling the molten metal to a temperature less than themelting point to solidify.
 4. A manufacturing method of minute metallicspheres described in claim 3, wherein the molten metal injected in saidgauger is cut by rubbing by the predetermined volume by rotational orslide action of said gauger to measure.
 5. A manufacturing method ofminute metallic spheres described in claim 1, wherein the molten metalin said gauger is discharged in a fluid at a temperature less than themelting point.
 6. A manufacturing method of minute metallic spheresdescribed in claim 5, wherein said fluid is an oil or an inerthigh-molecular liquid or an inert high-molecular steam or an inert gas.7. A manufacturing method of minute metallic spheres described in claim1, wherein said molten metal is pressurized and filled when said moltenmetal is injected in said gauger.
 8. A manufacturing apparatus of minutemetallic spheres for manufacturing minute metallic spheres of apredetermined size, comprising a heating means for heating and melting ametal to form a metallic sphere, a measurement means for measuring theinjected molten metal into a predetermined volume, and a cooling meansfor cooling said molten metal discharged from said gauger, to atemperature less than the melting point.
 9. A manufacturing apparatus ofminute metallic spheres described in claim 8, wherein said measurementmeans has a gauger of a predetermined volume in which the molten metalis injected, and is constructed such that said molten metal is cut byrubbing by the predetermined volume by sliding this gauger in contact.10. A manufacturing apparatus of minute metallic spheres described inclaim 8, wherein said cooling means is a fluid tank made of an oil or aninert high-molecular liquid or an inert high-molecular steam or an inertgas.
 11. A manufacturing method of minute metallic spheres formanufacturing minute metallic spheres of a predetermined size, wherein aminute metallic sphere is formed by discharging a molten metal from anopening portion, and dividing said molten metal discharged from saidopening portion into each predetermined volume.
 12. A manufacturingmethod of minute metallic spheres described in claim 11, wherein saidmolten metal is discharged from said opening portion by the own weightof said molten metal.
 13. A manufacturing method of minute metallicspheres described in claim 11, wherein said molten metal is dischargedfrom said opening portion by applying a pressure to said molten metal.14. A manufacturing method of minute metallic spheres described in claim11, wherein said molten metal divided is cooled to a temperature lessthan the melting point, and solidified into a sphere in the coolingprocess.
 15. A manufacturing method of minute metallic spheres describedin claim 11, wherein said molten metal is measured into a predeterminedquantity, and then said predetermined quantity of molten metal isdischarged from said opening portion.
 16. A manufacturing method ofminute metallic spheres for manufacturing minute metallic spheres of apredetermined size, having a step of heating and melting a metal to forma metallic sphere, and discharging the molten metal from an openingportion, a step of dividing said molten metal discharged from saidopening portion into each predetermined volume, and a step of coolingsaid molten metal divided to a temperature less than the melting pointto solidify.
 17. A manufacturing method of minute metallic spheresdescribed in claim 16, wherein said molten metal is discharged from saidopening portion by the own weight of said molten metal.
 18. Amanufacturing method of minute metallic spheres described in claim 16,wherein said molten metal is discharged from said opening portion byapplying a pressure to said molten metal.
 19. A manufacturing method ofminute metallic spheres described in claim 11, wherein said molten metaldivided is discharged in a fluid at a temperature less than the meltingpoint.
 20. A manufacturing method of minute metallic spheres describedin claim 19, wherein said fluid is an oil or an inert gas.
 21. Amanufacturing apparatus of minute metallic spheres for manufacturingminute metallic spheres of a predetermined size, comprising a heatingmeans for heating and melting a metal to form a metallic sphere, a meansfor discharging the molten metal from a predetermined opening portion, adivision means for dividing said molten metal having passed through saidopening portion, and a cooling means for cooling said molten metaldivided by said division means, to a temperature less than the meltingpoint.
 22. A manufacturing apparatus of minute metallic spheresdescribed in claim 21, wherein said cooling means is a fluid tank madeof an oil or an inert high-molecular liquid or an inert high-molecularsteam or an inert gas.
 23. A manufacturing apparatus of minute metallicspheres described in claim 21, wherein said molten metal is dischargedfrom said opening portion by the own weight of said molten metal.
 24. Amanufacturing apparatus of minute metallic spheres described in claim21, wherein said molten metal is discharged from said opening portion byapplying a pressure to said molten metal.
 25. A manufacturing method ofminute metallic spheres for manufacturing minute metallic spheres of apredetermined size, including a step of heating and melting a metal toform a metallic sphere, and injecting the molten metal in a measurementmeans by pressurizing, a step of cutting by rubbing the molten metalinjected in the measurement means by a predetermined volume to measure,and a step of discharging the measured molten metal from the measurementmeans by a fluid pressure, and cooling the molten metal to a temperatureless than the melting point to solidify.
 26. A manufacturing method ofminute metallic spheres described in claim 25, wherein, when the moltenmetal is injected, it is pressurized and supplied at a high pressurefrom one side of the measurement means, and the other side opposite toit is set to a low pressure.
 27. A manufacturing method of minutemetallic spheres described in claim 25, wherein the molten metalinjected in said measurement means is cut by rubbing by thepredetermined volume by rotational action of said measurement means tomeasure.
 28. A manufacturing method of minute metallic spheres describedin claim 25, wherein the molten metal in said measurement means isdischarged and cooled in a fluid at a temperature less than the meltingpoint, and solidified into a sphere in the cooling process.
 29. Amanufacturing apparatus of minute metallic spheres for manufacturingminute metallic spheres of a predetermined size, comprising a heatingmeans for heating and melting a metal to form a metallic sphere, a metalsupply means for pressurizing and supplying the molten metal molten bythe heating means, a measurement means supported so as to be rotatablerelatively to said metal supply means, for measuring the injected moltenmetal into a predetermined volume by its rotational action, and acooling means for cooling said molten metal discharged from saidmeasurement means, to a temperature less than the melting point.
 30. Amanufacturing apparatus of minute metallic spheres described in claim29, wherein said measurement means comprises a cylindrical rotationaldrum having a through hole in which the molten metal is injected, andmeasures the molten metal by slide rotational action in relation to saidmetal supply means.
 31. A manufacturing apparatus of minute metallicspheres described in claim 30, wherein said metal supply means has outerand inner blocks disposed outside and inside said measurement means,and, in relation to the measurement means sliding and rotating betweenthese, pressurizes and supplies the molten metal to the through holefrom the outer block side.
 32. A manufacturing apparatus of minutemetallic spheres described in claim 29, wherein said metal supply meanshas an injection passage provided in said outer block, and a storageportion disposed in said inner block oppositely to said injectionpassage.
 33. A manufacturing apparatus of minute metallic spheresdescribed in claim 31, wherein said inner block has a gas chamber fordischarging the molten metal injected in the through hole, from themeasurement means.
 34. A manufacturing apparatus of minute metallicspheres having a measurement unit in an upper portion of an oil vesseldisposed vertically, for forming a minute metallic sphere by solidifyinga molten metal discharged from this measurement unit, in an oil, whereinit has one or a plurality of cooling means in the lower part of saidmeasurement unit, and a lower portion of said oil vessel is cooled. 35.A manufacturing apparatus of minute metallic spheres described in claim34, wherein said cooling means is a cooling tube or a cooling jacketwound around said oil vessel in the lower part of said measurement unit.36. A manufacturing method of minute metallic spheres having ameasurement unit in an upper portion of an oil vessel disposedvertically, for forming a minute metallic sphere by solidifying a moltenmetal discharged from this measurement unit, in an oil, wherein one or aplurality of regions in the lower part of said oil vessel is cooled, andthe oil in each region is set and kept at a predetermined temperature.37. A manufacturing method of minute metallic spheres described in claim36, wherein the oil in said oil vessel is cooled by a cooling tube or acooling jacket wound around said oil vessel in the lower part of saidmeasurement unit.
 38. A manufacturing apparatus of minute metallicspheres having a measurement unit in an upper portion of an oil vesseldisposed vertically, for forming a minute metallic sphere by solidifyinga molten metal discharged from this measurement unit, in an oil, havingone or a plurality of moving-flow regulation means for physicallyregulating a convection of said oil in the oil vessel in the lower partof said measurement unit.
 39. A manufacturing method of minute metallicspheres described in claim 36, wherein said moving-flow regulation meansis a projecting piece projecting from an inner wall of said oil vessel.40. A manufacturing method of minute metallic spheres having ameasurement unit in an upper portion of an oil vessel disposedvertically, for forming a minute metallic sphere by solidifying a moltenmetal discharged from this measurement unit, in an oil, wherein aconvection of the oil in the oil vessel is physically regulated in oneor a plurality of portions in the lower part of said measurement unit,and the oil in each region regulated is set and kept at a predeterminedtemperature.
 41. A manufacturing apparatus of minute metallic sphereshaving a measurement unit in an upper portion of an oil vessel disposedvertically, for forming a minute metallic sphere by solidifying a moltenmetal discharged from this measurement unit, in an oil, having adispersion means for dispersing the molten metal, in the lower part ofsaid measurement unit.
 42. A manufacturing apparatus of minute metallicspheres described in claim 41, wherein, as said dispersion means, itincludes a bell-like member constructed so as to be able to oscillateand rotate.
 43. A manufacturing apparatus of minute metallic spheresdescribed in claim 41, wherein, as said dispersion means, it includes apropeller stirrer.
 44. A manufacturing apparatus of minute metallicspheres described in claim 41, wherein, as said dispersion means, itincludes a supersonic oscillator.
 45. A manufacturing method of minutemetallic spheres having a measurement unit in an upper portion of an oilvessel disposed vertically, for forming a minute metallic sphere bysolidifying a molten metal discharged from this measurement unit, in anoil, wherein, in the lower part of said measurement unit, the moltenmetal discharged from the measurement unit, is dispersed.
 46. Amanufacturing apparatus of minute metallic spheres having a measurementunit in an upper portion of an oil vessel disposed vertically, forforming a minute metallic sphere by solidifying a molten metaldischarged from this measurement unit, in an oil, comprising a moltenmetal supply apparatus for supplying a molten metal from which inclusionhas been removed, to the measurement unit.
 47. A manufacturing apparatusof minute metallic spheres described in claim 46, wherein said moltenmetal supply apparatus is constructed so as to blow out an inert gas tosaid molten metal in a pot, and catch and remove inclusion in saidmolten metal by the inert gas.
 48. A manufacturing apparatus of minutemetallic spheres described in claim 47, wherein said molten metal supplyapparatus further comprises a filter.
 49. A manufacturing apparatus ofminute metallic spheres having a measurement unit in an upper portion ofa vessel disposed vertically, for forming a minute metallic sphere bysolidifying a molten metal discharged from this measurement unit, in acooling medium put in the vessel, wherein said cooling medium comprisesan inert high-molecular liquid, an inert high-molecular steam and aninert gas.
 50. A manufacturing apparatus of minute metallic spheresdescribed in claim 49, wherein said cooling medium comprises an inertfluorine-type high-molecular liquid, and an inert fluorine-typehigh-molecular steam.
 51. A manufacturing apparatus of minute metallicspheres described in claim 49, wherein the specific gravity of saidcooling medium is 1.2 or more.
 52. A manufacturing apparatus of minutemetallic spheres having a measurement unit in an upper portion of avessel disposed vertically, for forming a minute metallic sphere bysolidifying a molten metal discharged from this measurement unit, in acooling medium put in the vessel, wherein said cooling medium comprisesan oil, and an inert high-molecular liquid put in the lower part of theoil.
 53. A manufacturing apparatus of minute metallic spheres describedin claim 52, wherein said cooling medium comprises an inertfluorine-type high-molecular liquid.
 54. A manufacturing apparatus ofminute metallic spheres described in claim 52, wherein the specificgravity of said cooling medium is 1.2 or more.
 55. A manufacturingapparatus of minute metallic spheres described in claim 52, wherein itincludes alcohol in said inert high-molecular liquid.
 56. Amanufacturing method of minute metallic spheres having a measurementunit in an upper portion of a vessel disposed vertically in which acooling medium is put, for forming a minute metallic sphere bysolidifying a molten metal discharged from this measurement unit, in thecooling medium put in the vessel, wherein an inert high-molecularliquid, an inert high-molecular steam and an inert gas are used as saidcooling medium, and said molten metal is cooled by said cooling mediumto solidify.
 57. A manufacturing method of minute metallic spheresdescribed in claim 56, wherein cooling is performed using an inertfluorine-type high-molecular liquid as said inert high-molecular liquid.58. A manufacturing method of minute metallic spheres described in claim56, wherein a liquid comprising said inert high-molecular liquid and anoil is used as said cooling medium, and, after cooling by said oil isperformed, cooling by said inert high-molecular liquid, an inerthigh-molecular steam and an inert gas are performed to solidify saidmolten metal.
 59. A manufacturing apparatus of minute metallic sphereshaving a measurement unit in an upper portion of a vessel disposedvertically, for forming a minute metallic sphere by solidifying a moltenmetal discharged from this measurement unit, in a cooling medium put inthe vessel, wherein the viscosity of said cooling medium is kept into 2cSt to 20 cSt at the temperature of 200° C. at which said molten metalis melted, and the dropping speed of said molten metal in said coolingmedium is decreased by the viscosity of said cooling medium.
 60. Amanufacturing method of minute metallic spheres described in claim 60,wherein said cooling medium is an oil, a mixture liquid in which aviscosity improver is added to an oil, or a mixture liquid in which aliquid of a high viscosity is added to an oil.
 61. A manufacturingmethod of minute metallic spheres in which a measured molten metal isdischarged in a vessel disposed vertically in which a cooling medium isput, and a minute metallic sphere is formed by solidifying said moltenmetal in said cooling medium, wherein the viscosity of said coolingmedium is kept into 2 cSt to 20 cSt at the temperature of 200° C. atwhich said molten metal is melted, and the dropping speed of said moltenmetal in said cooling medium is decreased by the viscosity of saidcooling medium.
 62. A manufacturing method of minute metallic spheresdescribed in claim 61, wherein an oil, a mixture liquid in which aviscosity improver is added to an oil, or a mixture liquid in which aliquid of a high viscosity is added to an oil, is used as said coolingmedium.
 62. A semiconductor device in which a semiconductor chip and asubstrate are electrically connected by minute metallic spheres of apredetermined size, wherein said minute metallic spheres are formed byinjecting a molten metal in a gauger of a predetermined volume tomeasure, and discharging the measured molten metal from the gauger tosolidify.
 63. A semiconductor device in which a semiconductor chip and asubstrate are electrically connected by minute metallic spheres of apredetermined size, wherein said minute metallic spheres aremanufactured by a method including a step of heating and melting a metalto form a metallic sphere, and injecting the molten metal in a gauger, astep of cutting by rubbing the molten metal injected in said gauger by apredetermined volume to measure, and a step of discharging the measuredmolten metal from the gauger, and cooling the molten metal to atemperature less than the melting point to solidify.